To obtain a heat radiating material having a light weight, electric insulation and thermal conductivity by blending aluminum nitride with high- density polyethylene, polyolefin thermoplastic elastomer or polypropylene to provide polymer heat radiating material.

Aluminum nitride is blended with high-density polyethylene, polyolefin thermoplastic elastomer or polypropylene to polymer heat radiating material. In this case, 10 to 80 pts.wt. of the nitride is blended with 100 pts.wt. of the polyethylene, polyolefin thermoplastic elastomer or polypropylene to provide polymer heat radiating material. The polymer heat radiating material is used to constitute a heat radiating component. This radiating material has a lighter weight than that of a metal heat sink. Further, it can be made to be lighter weight than that of other polymer heat radiating material using alumina or the like.