PURPOSE: To prevent generation of a cavity or a sink, by keeping 0.5W25 capacity part metallic fiber whose aspect ratio is 5W300 compounded, in a method performing injection molding of thick resin of more than 6mm thick.

CONSTITUTION: Injection molding is performed by making use of resin obtained by compounding 0.5W25 volume part metallic fiber (for example, aluminum fiber and copper fiber) whose aspect ratio (a length of the fiber/the diameter of the fiber) is 5W300 to 100 volume part thermoplastic resin. When the aspect ratio is more than 300 and a compounding quantity is more than 25 volume part, the molded article becomes bulky and kneading work becomes difficult. Even if a thick article is injected a cavity and a sink do not occur, through which the titled method is suitable for molding of a gear, a handle and a lever.