To provide a polyolefin resin molded article having improved long-term mechanical properties without depending on the polymerization technology of polyolefin resin.

The polyolefin resin molded body is prepared by heating/kneading a polyolefin resin composition followed by molding the kneaded composition. The polyolefin resin composition includes a polyolefin thermoplastic resin, an organic peroxide having a one-minute half-life temperature of 140-220C, and a layer silicate treated with an organic compound having an unsaturated double bond.