A resin molded body includes: a polyolefin element formed of polyolefin, including a crystalline region and an amorphous region; and a hydrophilic copolymer contained in at least part of a surface of the polyolefin element, the hydrophilic copolymer including a copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) of 45% or greater on a mole fraction basis and at least one other monomer. In the resin molded body, the MPC polymer is immersed through the surface by applying heat treatment.