1. An epoxy resin composition comprising the following
constituent elements [A] and [B], wherein the epoxy resin
composition cured into a cured product has a rubbery state
elastic modulus in a dynamic viscoelasticity evaluation of 10
MPa or less, and the cured product has a glass transition
temperature of 95°C or higher:
[A] a bifunctional or higher functional epoxy resin containing an aromatic ring; and
[B] an amine hardener or an acid anhydride hardener.
2. The epoxy resin composition according to claim 1,
comprising the following constituent elements [al] and [a2] as
the constituent element [A], and comprising the following
constituent elements [bl] and [b2] as the constituent element
[B] :
[al] a trifunctional or higher functional aromatic epoxy resin;
[a2] an optionally substituted glycidyl aniline;
[bl] an aromatic diamine having a substituent at an ortho position of each amino group or a cycloalkylamine having a substituent on a carbon atom adjacent to a carbon atom bonded to each amino group; and
[b2] at least one amine selected from the group consisting

of 4,4'-methylenebiscyclohexylamine,
1,3-bisaminomethylcyclohexane,
N-cyclohexyl-1,3-propanediamine, and isophoronediamine.
3. The epoxy resin composition according to claim 2, comprising 20 to 40 parts by mass of the constituent element [al] and 20 to 60 parts by mass of the constituent element [a2] in 100 parts by mass of the total epoxy resin.
4. The epoxy resin composition according to claim 1, comprising the following constituent element [al] as the constituent element [A], and comprising the following constituent elements [bl] and [b3] as the constituent element [B] :
[al] a trifunctional or higher functional aromatic epoxy resin;
[bl] an aromatic diamine having a substituent at an ortho position of each amino group or a cycloalkyldiamine having a substituent on a carbon atom adjacent to a carbon atom bonded to each amino group; and
[b3] an aromatic monoamine represented by the following general formula (I) or (II): [Chemical Formula 1]

wherein R1 is a substituent selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, and R is a substituent selected from an oxygen atom, a sulfonyl group, and a methylene group; or [Chemical Formula 2]
wherein R3 is a substituent selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.
5. The epoxy resin composition according to claim 4, wherein the constituent element [b3] is an aromatic monoamine represented by the general formula (I).
6. The epoxy resin composition according to claim 1, comprising the following constituent element [a3] as the constituent element [A], and comprising the following constituent elements [b4] and [b5] as the constituent element [B] :

[a3] a bifunctional or higher functional epoxy resin having a fluorene structure;
[b4] an acid anhydride represented by the following general formula (III):
wherein R4 represents any one of linear or branched alkyl, alkenyl, and alkynyl groups having 6 to 16 carbon atoms; and [b5] at least one acid anhydride selected from the group consisting of tetrahydrophthalic anhydride,
methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.
7. The epoxy resin composition according to claim 6, having a ratio of parts by mass of the constituent element [b4] to the sum of parts by mass of the constituent elements [b4] and [b5] of 0.3 to 0.6.
8. The epoxy resin composition according to claim 1, comprising at least one of the following constituent elements [a2] and [a4] as the constituent element [A], and further

comprising the following constituent element [C]:
[a2] an optionally substituted diglycidyl aniline;
[a4] tetraglycidyl diaminodiphenylmethane; and
[C] a monofunctional epoxy resin which is a phenyl
glycidyl ether substituted with a tert-butyl group, a sec-butyl
group, an isopropyl group, or a phenyl group.
9. The epoxy resin composition according to claim 8, comprising 20 to 50 parts by mass of the constituent element [C] in 100 parts by mass of the total epoxy resin.
10. The epoxy resin composition according to claim 8 or 9, comprising the constituent elements [a2] and [a4] as the constituent element [A].
11. The epoxy resin composition according to any one of claims 8 to 10, wherein the constituent element [B] is an acid anhydride hardener.
12. The epoxy resin composition according to claim 11, comprising a compound having a norbornene backbone or a norbornane backbone as the constituent element [B].
13. The epoxy resin composition according to any one of claims 8 to 10, wherein the constituent element [B] is an amine hardener,

and the epoxy resin composition comprises the following constituent element [bl] as the constituent element [B]:
[bl] an aromatic diamine having a substituent at an ortho position of an amino group or a cycloalkyldiamine having a substituent on a carbon atom adjacent to a carbon atom having an amino group.
14. The epoxy resin composition according to claim 13, further comprising an aliphatic polyamine having an alkylene glycol structure as the constituent element [B].
15. The epoxy resin composition according to claim 13, further comprising isophoronediamine as the constituent element [B].
16. The epoxy resin composition according to any one of claims 1 to 3 or 6 to 15, having a viscosity at 25°C of 2,000 mPa-s or less.
17. The epoxy resin composition according to claim 4 or 5, having a viscosity at 25°C of 3,000 mPa-s or less.
18. A fiber reinforced material comprising a cured product of the epoxy resin composition according to any one of claims 1 to 17 and a reinforcing fiber.

19 . A molded article comprising the fiber reinforced material . according to claim 18.
20. A pressure vessel comprising the fiber reinforced material according to claim 18.