An antifouling composition comprising a silane-based compound represented by the following formula (a): Formula (a): Si(OR 1) p (X 1) 4-p wherein, R 1 represents an alkyl group having 1 to 6 carbon atoms, and in the case where plural R 1 s are present, the plural R 1 s may be the same as or different from each other; X 1 represents a halogen atom, and in the case where plural X 1 s are present, the plural X 1 s may be the same as or different from each other; and p represents an integer of 0 to 4, a silane-based compound represented by the following formula (b): Formula (b): R 2 Si(OR 3) q (X 2) 3-q wherein, R 2 represents an alkyl group having 4 to 22 carbon atoms, and the alkyl group does not have a substituent, or has a substituent selected from the group which consists of a chlorine atom, a bromine atom, an iodine atom; a hydroxyl group; a nitro group; an amino group; a cyano group; a thiol group; an epoxy group; a glycidoxy group; a (meth)acryloyloxy group; a cycloalkyl group having 3 to 12 ring-forming carbon atoms; an aryl group having 6 to 12 ring-forming carbon atoms; a heteroaryl group having 6 to 12 ring-forming atoms, which contains a hetero atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom; an alkoxy group having 1 to 6 carbon atoms; and an aryloxy group having 6 to 12 ring-forming carbon atoms; R 3 represents an alkyl group having 1 to 6 carbon atoms, and in the case where plural R 3 s are present, the plural R 3 may be the same as or different from each other; X 2 represents a halogen atom, and in the case where plural X 2 s are present, the plural X 2 s may be the same as or different from each other; and q represents an integer of 0 to 3, and at least one metal catalyst selected from the group consisting of a titanium-based catalyst, an aluminum-based catalyst, a tin-based catalyst, and a zinc-based catalyst, wherein the content of the component in the antifouling composition is 0.3 to 10.0 mol% based on 100 mol% of the total amount of the component and the component, and the antifouling composition satisfying the following relational expression: 1.5 ≤ y ≤ 2 ⁢ x + 1 wherein, x indicates the carbon number of the alkyl group that is selected for R 2 in the formula (b) representing the silane-based compound and indicates a number of 4 to 22; and y indicates a blending amount ratio / in a molar ratio of the silane-based compound to the silane-based compound. R 1 represents an alkyl group having 1 to 6 carbon atoms, and in the case where plural R 1 s are present, the plural R 1 s may be the same as or different from each other; X 1 represents a halogen atom, and in the case where plural X 1 s are present, the plural X 1 s may be the same as or different from each other; and p represents an integer of 0 to 4, a silane-based compound represented by the following formula (b): Formula (b): R 2 Si(OR 3) q (X 2) 3-q R 2 represents an alkyl group having 4 to 22 carbon atoms, and the alkyl group does not have a substituent, or has a substituent selected from the group which consists of a chlorine atom, a bromine atom, an iodine atom; a hydroxyl group; a nitro group; an amino group; a cyano group; a thiol group; an epoxy group; a glycidoxy group; a (meth)acryloyloxy group; a cycloalkyl group having 3 to 12 ring-forming carbon atoms; an aryl group having 6 to 12 ring-forming carbon atoms; a heteroaryl group having 6 to 12 ring-forming atoms, which contains a hetero atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom; an alkoxy group having 1 to 6 carbon atoms; and an aryloxy group having 6 to 12 ring-forming carbon atoms; R 3 represents an alkyl group having 1 to 6 carbon atoms, and in the case where plural R 3 s are present, the plural R 3 may be the same as or different from each other; X 2 represents a halogen atom, and in the case where plural X 2 s are present, the plural X 2 s may be the same as or different from each other; and q represents an integer of 0 to 3, and at least one metal catalyst selected from the group consisting of a titanium-based catalyst, an aluminum-based catalyst, a tin-based catalyst, and a zinc-based catalyst, wherein the content of the component in the antifouling composition is 0.3 to 10.0 mol% based on 100 mol% of the total amount of the component and the component, and the antifouling composition satisfying the following relational expression: 1.5 ≤ y ≤ 2 ⁢ x + 1 wherein, x indicates the carbon number of the alkyl group that is selected for R 2 in the formula (b) representing the silane-based compound and indicates a number of 4 to 22; and y indicates a blending amount ratio / in a molar ratio of the silane-based compound to the silane-based compound.