A semiconductor device and method of manufacturing the semiconductor device is disclosed in which the tradeoff relationship between the Eoff and the turning OFF dV/dt is improved at a low cost using a trench embedding method. The method comprises a step of forming a parallel pn layer that is a superjunction structure using a trench embedding method and a step of ion implantation into an upper part of an n type semiconductor layer, i.e., an n type column, forming a high concentration n type semiconductor region. This method improves the trade-off relationship between the Eoff and the turning OFF dV/dt as compared with a high concentration n type semiconductor region formed of an epitaxial layer. This method achieves shorter process time and lower cost in manufacturing because it eliminates the redundant repeating of steps performed in the conventional method of forming a superjunction structure through multi-stage epitaxial growth.