1. A copolymer which is obtainable by polymerizing a monomer mixture containing at least compounds of the following formulae (A), (B) and (C):
wherein
T\ Tb, Tc, Ual, If2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Qa and Qb each independently represent a single bond, an ester bond or an amide bond, 10 Q° represents a single bond, an ether bond or an ester bond;
Ra and Rb each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s), R° represents a
linear or branched alkyl group having 1 to 18 carbon atoms, a cyclic hydrocarbon
group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an 15 aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14
carbon atoms, where the above-mentioned aryl portion may be substituted by a linear
or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a
halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an 20 inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and
m represents an integer of 0 to 6.
2. The copolymer according to Claim 1, wherein the copolymer is obtainable by polymerizing a monomer mixture further containing a compound of the following 25 formula (D) or (E):

wherein
Td, Te and Ue each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms;
Rd and Re each independently represent a linear or branched alkylene group having 1 to 10 carbon atoms which may be substituted by a halogen atom(s); and n represents an integer of 1 to 6.
3. A composition for forming a coating film which comprises
(i) a copolymer which contains a recurring unit containing an organic group of the
following formula (a), a recurring unit containing an organic group of the following
formula (b) and a recurring unit containing an organic group of the following formula
(c):
wherein
UaI, Uii2, Ubi, Ub2 and Ub3 each independently represent a hydrogen atom or a linear or
branched alkyl group having 1 to 5 carbon atoms;
Rc represents a linear or branched alkyl group having 4 to 18 carbon atoms, a cyclic
hydrocarbon group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon
atoms, an aralkyl group having 7 to 14 carbon atoms or an aryloxyaikyl group having

7 to 14 carbon atoms, where the above-mentioned aryl portion may be substituted by a
linear or branched alkyl group having 1 to 5 carbon atoms which may be substituted
by a halogen atom(s); and
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion, and
(ii) a solvent.
4. The composition according to Claim 3, wherein the copolymer contains recurring units of the following formulae (al), (bl) and (cl):
wherein
Ta, Tb, Tc, Ual, Ua2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Qa and Qb each independently represent a single bond, an ester bond or an amide bond,
Qc represents a single bond, an ether bond or an ester bond;
Ra and Rb each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s), R° represents a
linear or branched alkyl group having 4 to 18 carbon atoms, an alicyclic hydrocarbon
group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an
aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14
carbon atoms, where the above-mentioned aryl portion may be substituted by a linear
or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a
halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and

m represents an integer of 0 to 6.
5. A coating film obtainable by a method which comprises a process of coating a composition for forming a coating film which contains a copolymer containing a recurring unit containing an organic group of the following formula (a), a recurring unit containing an organic group of the following formula (b) and a recurring unit containing an organic group of the following formula (c):
wherein
Ual, Ua\ Ubi, Ub2 and Ub3 each independently represent a hydrogen atom or a linear or
branched alkyl group having 1 to 5 carbon atoms;
Rc represents a linear or branched alkyl group having 4 to 18 carbon atoms, an
alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aryl group having 6 to 10
carbon atoms, an aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group
having 7 to 14 carbon atoms, where the above-mentioned aryl portion may be
substituted by a linear or branched alkyl group having 1 to 5 carbon atoms which may
be substituted by a halogen atom(s); and
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion, and
a solvent onto a substrate.
6. The coating film according to Claim 5, wherein the copolymer contains recurring units of the following formulae (al), (bl) and (cl):

wherein
Ta, Tb, Tc, Ua\ U!i2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Qa and Q' each independently represent a single bond, an ester bond or an amide bond,
Qc represents a single bond, an ether bond or an ester bond;
Rcl and R each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s), Rc represents a
linear or branched alkyl group having 4 to 18 carbon atoms, an alicyclic hydrocarbon
group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an
aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14
carbon atoms, where the above-mentioned aryl portion may be substituted by a linear
or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a
halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and
m represents an integer of 0 to 6.
7. The coating film according to Claim 5 or 6, wherein the method contains a process of provisionally adjusting a pH of the composition for forming a coating film.
8. The coating film according to any one of Claims 5 to 7, wherein the method further contains a process of washing the film obtained after a drying process by at least one kind of a solvent selected from the group consisting of water and an aqueous solution containing an eleclrolyte(s).

9. The coating film according to any one of Claims 5 to 8, wherein the film has a function of inhibiting adhesion of a biological substance.
5 10. A sol which comprises a copolymer containing a recurring unit containing an organic group of the following formula (a), a recurring unit containing an organic group of the following formula (b) and a recurring unit containing an organic group of the following formula fc):
wherein
Ual, Ua2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or a linear or
branched alkyl group having 1 to 5 carbon atoms;
Rc represents a linear or branched alkyl group having 4 to 18 carbon atoms, an
alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aryl group having 6 to 10
carbon atoms, an aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group
having 7 to 14 carbon atoms, where the above-mentioned aryl portion may be
substituted by a linear or branched alkyl group having 1 to 5 carbon atoms which may
be substituted by a halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion.
11. The sol according to Claim 10, wherein an average particle diameter in particle diameter distribution measured by a dynamic light scattering method is 2 nm or more and 500 nm or less.
12. A method for manufacturing a coating film comprising a process of coating a composition for forming a coating film which comprises a copolymer containing a recurring unit containing an organic group of the following formula (a), a recurring

unit containing an organic group of the following formula fb) and a recurring unit containing an organic group of the following formula (c):
wherein
Ual, Ua , Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or a linear or
branched alkyl group having 1 to 5 carbon atoms;
Rc represents a linear or branched alkyl group having 4 to 18 carbon atoms, a
cycloalkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 10 carbon
atoms, an aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having
7 to 14 carbon atoms, where, the above-mentioned aryl portion may be substituted by
a linear or branched alkyl group having 1 to 5 carbon atoms which may be substituted
by a halogen atom(s); and
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion, and
a solvent, onto a substrate.
13. A method for producing a varnish containing a copolymer which comprises a process of adding dropwise a mixture containing compounds of the following formulae (A), (B) and (C):

wherein
Ta, Tb, Tc, Ua!, Ua2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Qa and Q1 each independently represent a single bond, an ester bond or an amide bond,
Qc represents a single bond, an ether bond or an ester bond;
Ra and Rb each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s), Rc represents a
linear or branched alkyl group having 4 to 18 carbon atoms, an alicyclic hydrocarbon
group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an
aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14
carbon atoms, where, the above-mentioned aryl portion may be substituted by a linear
or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a
halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and
m represents an integer of 0 to 6,
a solvent and a polymerization initiator
to a solvent which has been maintained at a temperature higher than a 10 hour half-life
temperature of the polymerization initiator, and reacting these.
14. A method for producing a copolymer which comprises a process of polymerizing a monomer mixture containing at least compounds of the following formulae (A), (B) and (C):

wherein
Ta, T\ TC, Ual, Ua2, Ubl, Ub2 and Ub3 each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Q!l and Qb each independently represent a single bond, an ester bond or an amide bond,
Qc represents a single bond, an ether bond or an ester bond;
Ra and R each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s), Rc represents a
linear or branched alkyl group having 1 to 18 carbon atoms, a cyclic hydrocarbon
group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an
aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14
carbon atoms, where the above-mentioned aryl portion may be substituted by a linear
or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a
halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an
inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and
m represents an integer of 0 to 6.
15. The producing method according to Claim 14, wherein the copolymer is obtainable by polymerizing a monomer mixture which further contains a compound of the following formula (D) or (E):

wherein
T\ T^ and Ue each independently represent a hydrogen atom or a linear or branched
alkyl group having 1 to 5 carbon atoms;
R and Re each independently represent a linear or branched alkylene group having 1
to 10 carbon atoms which may be substituted by a halogen atom(s); and n represents
an integer of 1 to 6.
16. A method for producing a sol which comprises a process of polymerizing a monomer mixture containing at least compounds of the following formulae (A), (B)
wherein
T'1, T\ T°, Ua , Ua~, U , U " and U' each independently represent a hydrogen atom or
a linear or branched alkyl group having 1 to 5 carbon atoms;
Qa and Q1 each independently represent a single bond, an ester bond or an amide bond,
QL represents a single bond, an ether bond or an ester bond;
R'1 and R1 each independently represent a linear or branched alkylene group having 1

to 10 carbon atoms which may be substituted by a halogen atom(s), Rc represents a linear or branched alkyl group having 1 to 18 carbon atoms, a cyclic hydrocarbon group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 14 carbon atoms or an aryloxyalkyl group having 7 to 14 carbon atoms, where the above-mentioned aryl portion may be substituted by a linear or branched alkyl group having 1 to 5 carbon atoms which may be substituted by a halogen atom(s);
An" represents an anion selected from the group consisting of a halide ion, an inorganic acid ion, a hydroxide ion and an isothiocyanate ion; and m represents an integer of 0 to 6.
17. The copolymer according to Claim 1 or 2, wherein which is for forming a coating film having a function of inhibiting adhesion of a biological substance.
18. The composition according to Claim 3 or 4, which is for forming a coating film having a function of inhibiting adhesion of a biological substance.
19. The sol according to Claim 10 or 11, which is for forming a coating film having a function of inhibiting adhesion of a biological substance.
20. The manufacturing method according to Claim 12, wherein the coating film has a function of inhibiting adhesion of a biological substance.
21. The producing method according to Claim 13, wherein the varnish is for forming a coating film having a function of inhibiting adhesion of a biological substance.
22. The producing method according to Claim 14 or 15, wherein the copolymer is for forming a coating film having a function of inhibiting adhesion of a biological substance.
23. The producing method according to Claim 16, wherein the sol is for forming a coating film having a function of inhibiting adhesion of a biological substance.