A semiconductor device includes: a substrate having a groove formed on a main surface; a drift region of a first conductivity type, the drift region having a portion disposed at a bottom part; a well region of a second conductivity type, the well region being disposed in one sidewall to be connected to the drift region; a first semiconductor region of the first conductivity type, the first semiconductor region being disposed on a surface of the well region in the sidewall to be away from the drift region; a second semiconductor region of the first conductivity type, the second semiconductor region being disposed to be opposed to the well region via the drift region; and a gate electrode opposed to the well region, the gate electrode being disposed in a gate trench that has an opening extending over the upper surfaces of the well region and the first semiconductor region.