An antifouling coating composition, comprising: a copolymer A; a carboxylic acid silyl ester B, being a silyl ester of a carboxylic acid other than an ethylenically unsaturated carboxylic acid and having triisopropylsilyl as a silyl group; a monocarboxylic acid metal salt C; wherein: the copolymer A is obtained by copolymerizing a mixture of a monomer (a), a monomer (b) and an ethylenically unsaturated monomer (c); the monomer (a) is represented by general formula; in the general formula, three Rs are the same or different, and each of the Rs is a C3 to C8 hydrocarbon group branched at α-position or β-position, and the hydrocarbon group is an aliphatic or aromatic group and has a linear, branched, or cyclic structure, and X represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group; the monomer (b) is represented by general formula; Y − R in the general formula, R represents a C2 to C10 alkyl group having an oxygen atom or a C2 to C10 aryl group having an oxygen atom, and Y represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group. a copolymer A; a carboxylic acid silyl ester B, being a silyl ester of a carboxylic acid other than an ethylenically unsaturated carboxylic acid and having triisopropylsilyl as a silyl group; a monocarboxylic acid metal salt C; wherein: the copolymer A is obtained by copolymerizing a mixture of a monomer (a), a monomer (b) and an ethylenically unsaturated monomer (c); the monomer (a) is represented by general formula; in the general formula, three Rs are the same or different, and each of the Rs is a C3 to C8 hydrocarbon group branched at α-position or β-position, and the hydrocarbon group is an aliphatic or aromatic group and has a linear, branched, or cyclic structure, and X represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group; the monomer (b) is represented by general formula; Y − R in the general formula, R represents a C2 to C10 alkyl group having an oxygen atom or a C2 to C10 aryl group having an oxygen atom, and Y represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group. the copolymer A is obtained by copolymerizing a mixture of a monomer (a), a monomer (b) and an ethylenically unsaturated monomer (c); the monomer (a) is represented by general formula; in the general formula, three Rs are the same or different, and each of the Rs is a C3 to C8 hydrocarbon group branched at α-position or β-position, and the hydrocarbon group is an aliphatic or aromatic group and has a linear, branched, or cyclic structure, and X represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group; the monomer (b) is represented by general formula; Y − R in the general formula, R represents a C2 to C10 alkyl group having an oxygen atom or a C2 to C10 aryl group having an oxygen atom, and Y represents an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group.