To provide a metal resin composite part which has strength equal to a metal part and is lightweight.

The metal resin composite part is prepared by blending and kneading a resin, a crosslinkable multifunctional monomer used as a crosslinking aid of the resin, and a metal filler surface-treated with triazines which is dispersed in the resin, molding the resulting kneaded product in a mold, crosslinking the resin by irradiation of radiation after molding, and heat-treating the crosslinked resin molding at 100°C or higher. The metal resin composite part has tensile strength of 100 MPa or more and specific gravity of 3 or less.