meth)acrylic block copolymer

To provide a (meth)acrylic block copolymer which has a fast curing speed when irradiated with an active energy ray, and which has a low degree of viscosity. The (meth)acrylic block copolymer comprises: a methacrylic polymer block (a1) and a methacrylic polymer block (a2), each having an active energy ray-curable group that includes a partial structure (1) shown in general formula (1); and an acrylic polymer block (B) which is positioned between the methacrylic polymer block (a1) and the methacrylic polymer block (a2), and which does not have an active energy ray-curable group. The (meth)acrylic block copolymer contains: at least 30mass% of methyl methacrylate-derived monomeric units with respect to the total monomeric units of the methacrylic polymer block (a1) and the methacrylic polymer block (a2); and at least 40mass% of monomeric units derived from acrylate alkyl ester having an alkyl group with a carbon number of 6 or above with respect to total monomeric units of the acrylic polymer block (B). (In formula (1), R 1 represents a hydrogen atom or a hydrocarbon group with a carbon number 1-20.)