Performance of a semiconductor device is improved. Graphene particles are mixedly added in a sealing resin covering a semiconductor chip. The graphene particles are thus mixedly added in the sealing resin, thereby thermal conduction of the sealing resin is improved, and thus radiation performance of the semiconductor device can be improved. Graphene is a sheet of sp2 bonded carbon atoms having a monolayer thickness. Graphene has a structure where hexagonal lattices, each of which is formed of carbon atoms and bonds of the carbon atoms, are planarly spread. Graphene is preferably used as heat transfer filler because of its high thermal conductivity and light weight.