To make it possible to attempt to effectively recycle wasted plastic bottle, to mold the material by injection or extrusion molding and to improve the strength and processability by using the comminuted material of the bottle as the aggregate of other thermoplastic resin molding material.

30 to 60wt.% of comminuted material of plastic bottle comminuted to 1mm×1mm or less and dried by the frictional heat in the case of agitating by agitating impact blade, and 40 to 70wt.% of polyethylene, polypropylene or polyvinyl chloride are mixed together by the blade. It is gelatinized and kneaded by the frictional heat of 190 to 220°C generated by the mixture. A molding die 10 obtained by cooling the gelatinized and kneaded material and granulating it to pellet state having a particle size of 15mm or less has a molding chamber 22 laminated on the inner wall with a fluororesin sheet 24 or coated with fluororesin.