A method of producing thermoplastic resin composite material in which a main base material containing thermoplastic resin and a sheet-like shaped auxiliary base material are integrally molded and are made into composite material. The production method includes the steps of: heating the auxiliary base material (step S1); disposing the heated auxiliary base material in a mold (step S2); disposing the main base material in the mold via the auxiliary base material (step S3); closing the mold, and pressing together and integrally molding the auxiliary base material and the main base material (step S4); and taking out the integrally-molded thermoplastic resin composite material from the mold.