In addressing this problem, we succeeded in producing polylactic acid of higher thermal conductivity using a significantly lower amount of added carbon fiber (≥ 10%), using polylactic acid (a type of bioplastic) as a base resin, and an original plant-based binding agent to achieve reticulate (mesh-shaped) bonding (cross-linking) of carbon fibers in resin. (See Fig. 9.) This material has a low specific specific gravity (≤ 1.3)close to that of polylactic acidand combines a thermal diffusivity that is better than that of stainless steel, while keeping the typical light weight of plastics. (See Fig. 10.) Furthermore, we achieved anisotropic heat transfer in the planar directiona feature that cannot be achieved with metalsby means of orienting the carbon fibers during the formation process. (See Fig. 11.) When this material is used for the housing of today's increasingly small and thin electronic equipments, these features will enable good heat dissipation from the housing without allowing localized points of high temperature. They will also prove useful in various other fields of application.