A semiconductor device includes a semiconductor substrate in which a first region having a freewheeling diode arranged therein, second regions having an IGBT arranged therein, and a withstand-voltage retention region surrounding the first region and the second regions in plan view are defined. The semiconductor substrate has a first main surface and a second main surface. The semiconductor substrate includes an anode layer having a first conductivity type, which is arranged in the first main surface of the first region, and a diffusion layer having the first conductivity type, which is arranged in the first main surface of the withstand-voltage retention region adjacently to the anode layer. A first trench is arranged in the first main surface on a side of the anode layer with respect to a boundary between the anode layer and the diffusion layer.