Provided is an antifouling composition including a tetrafunctional silane-based compound (A) having a specified structure, a trifunctional silane-based compound having a specified structure, and at least one metal catalyst (C) selected from the group consisting of a titanium-based catalyst, an aluminum-based catalyst, a tin-based catalyst, and a zinc-based catalyst, the antifouling composition satisfying the following relational expression (1). 1.5 ≤ y ≤ 2 x + 1
In the expression, x indicates the carbon number of an alkyl group that is selected for R 2 in the formula (b) representing the silane-based compound (B) and indicates a number of 4 to 22; and y indicates a blending amount ratio (A)/(B) in a molar ratio of the silane-based compound (A) to the silane-based compound (B).