To produce a thermoplastic resin molding which, when electromagnetic wave irradiation molding is carried out, performs smooth packing of thermoplastic resin particles into a cavity, can prevent the occurrence of faults such as burning, and is excellent in quality including appearance, shape, and surface accuracy and mechanical strengths.

A thermoplastic resin particle composition 6A is used in a process in which it is packed in the cavity 22 of a rubber mold 2 made of a rubber material and heated/melted by being irradiated with electromagnetic waves including a wavelength domain of 0.78-2 μm. The thermoplastic resin particle composition 6A contains thermoplastic resin particles 61 and fine particles 62 of inorganic powdered matter and/or a lubricant. The number average particle size of the thermoplastic resin particles 61 is 200-3,000 μm, and the number average particle size of the fine particles 62 is 0.5-50 μm. In the thermoplastic resin particle composition 6A, 0.1-10 pts.mass of the fine particles 62 are contained per 100 pts.mass of the thermoplastic resin particles 61.