In order to simplify the equipment for heating a thermosetting resin or a thermoplastic resin and to reduce manufacturing costs of a molded resin article by saving energy, this resin composite material (1A-1I) is formed by combining a fibrous reinforcing material (2) and a thermosetting or thermoplastic matrix resin (3), wherein a metal nanomaterial (4) which self-heats after absorbing electromagnetic waves is added to the matrix resin (3). The frequency of the electromagnetic waves is preferably within the range of 3 MHz to 3 GHz. The metal nanomaterial (4) is preferably nanofibers or nanocoils, and the material is preferably platinum or gold.