Polyolefin-based resin composition and use thereof

A polyolefin-based resin composition of the invention has an addition polymerization-based block copolymer (I) and a polyolefin-based resin (II). The addition polymerization-based block copolymer (I) is selected from block copolymers comprising at least one polymer block A and at least one polymer block B, and the hydrogenated products thereof. The polymer block A comprises an aromatic vinyl compound unit comprising at least 1% by mass of an alkylstyrene-derived structural unit (a), in which at least one alkyl group having 1 to 8 carbon atoms is bound to a benzene ring. The polymer block B comprises a conjugated diene compound unit. A moiety of polymer block A can undergo crosslinking upon exposure to an active energy ray. After being molded into a desired shape, the composition is exposed to an active energy ray to carry out the crosslinking reaction. The composition exhibits flexibility, heat resistance, mechanical properties and solvent resistance in a well-balanced manner.