A (meth)acrylic block copolymer includes a methacrylic polymer block including at least one structural unit derived from a dimethacrylate according to formula (2): where R1 is a methyl group, R2 and R3 are each independently a hydrocarbon group having 1 to 6 carbon atoms, and n is an integer of 1 to 5, and a (meth)acrylic polymer block having no active energy ray curable groups. A method of preparing the (meth)acrylic block copolymer and an active energy ray curable composition are provided.