WE CLAIM:
1. A biological component adhesion-suppressing material
comprising:
a substrate having a functional layer with a polymer immobilized on a surface that is in contact with a biological component, the polymer containing a saturated aliphatic monocarboxylic acid vinyl ester unit,
wherein
the number of carbon atoms in an aliphatic chain in a saturated aliphatic monocarboxylic acid ion signal detected in compositional analysis of the surface of the functional layer by a TOF-SIMS apparatus is 2 to 20, and
a peak derived from an ester group is present in XPS measurement of the surface of the functional layer.
2. The biological component adhesion-suppressing material according to claim 1, wherein the saturated aliphatic monocarboxylic acid ion signal is derived from a saturated aliphatic monocarboxylic acid vinyl ester homopolymer or a copolymer containing a saturated aliphatic monocarboxylic acid vinyl ester, and has antithrombogenicity.
3. The biological component adhesion-suppressing

material according to claim 1 or 2, wherein the number of carbon atoms in an aliphatic chain in the saturated aliphatic monocarboxylic acid ion signal is 2 to 9.
4. The biological component adhesion-suppressing •material according to any one of claims 1 to 3, wherein in XPS measurement of the surface of the functional layer, the area percentage of the carbon peak derived from an ester group is 0.5 to 25 (atomic%) where the total area of peaks derived from carbon is 100 (atomic%).
5. The biological component adhesion-suppressing material according to any one of claims 1 to 4, wherein in ATR-IR measurement of the surface of the functional layer, a peak is present in each of both a range of 1711 to 1751 cm-1 and a range of 1549 to 1620 cm-1, and the average of the ratio of the peak area Ac=o in the range of 1711 to 1751 cm-1 to the peak area Ac=c in the range of 1549 to 1620 cm-1 (Ac=o/Ac=c) is 0.01 to 1.0.
6. The biological component adhesion-suppressing material according to claim 5, wherein the peak present in the range of 1549 to 1620 cm-1 is derived from aromatic groups in a polysulfone-based polymer.

7. The biological component adhesion-suppressing material according to claim 5 or 6, wherein a peak is present in a range of 1617 to 1710 cm"1 in ATR-IR measurement of the surface of the functional layer.
8. The biological component adhesion-suppressing material according to claim 7, wherein the peak present in the range of 1617 to 1710 cm-1 is derived from an amide bond in a hydrophilic polymer containing a vinylpyrrolidone unit, a vinylcaprolactam unit, a vinylacetamide unit or an acrylamide unit.
9. The biological component adhesion-suppressing material according to any one of claims 1 to 8, which is used for blood purification; and
10. A blood purifier comprising the biological component adhesion-suppressing material according to any one of claims 1 to 9.