Stress is exerted to the SiC crystal in the region, in which the carriers of a SiC semiconductor device flow, to change the crystal lattice intervals of the SiC crystal. Since the degeneration of the conduction bands in the bottoms thereof is dissolved, since the inter-band scattering is prevented from causing, and since the effective electron mass is reduced due to the crystal lattice interval change, the carrier mobility in the SiC crystal is improved, the resistance of the SiC crystal is reduced and, therefore, the on-resistance of the SiC semiconductor device is reduced.