A semiconductor device includes a diode provided with: a drift layer being a first conductivity type; a cathode region being provided in a back face side of the drift layer and being the first conductivity type; a second conductivity type region provided in a surface layer part of the drift layer; multiple trenches dividing the second conductivity type region into pieces by being provided deeper than the second conductivity type region, and configuring an anode region; a gate insulation film provided in a surface of the trench; a gate electrode provided in a surface of the gate insulation film; an upper electrode electrically connected with the anode region; and a lower electrode electrically connected with the cathode region. A width between the trenches is narrowest in the drift layer is defined as a mesa width. The mesa width is set to be equal to or greater than 0.3 μm.