1. A semiconductor device, comprising: a semiconductor deposition layer with a first conductivity type provided on a semiconductor substrate with a first conductivity type, and having an impurity concentration lower than that of the semiconductor substrate; a first well with a second conductivity type and a second well with a second conductivity type separated from the first well, the first and second wells being provided in a surface of the semiconductor deposition layer, the first well being provided so as to surround a first trench which is formed substantially perpendicularly in the surface of the semiconductor deposition layer, the second well being provided so as to surround a second trench which is formed substantially perpendicularly in the surface of the semiconductor deposition layer, a depth of the first and second wells being deeper than that of the first and second trenches; a gate electrode provided on a gate insulator film; a first source region with a first conductivity type and a second source region with a second conductivity type, the first and second source regions being provided in a surface of each of the first and second wells, the first source region having an impurity concentration higher than that of the semiconductor deposition layer, the second source region having an impurity concentration higher than that of the first and second wells, a depth of the first and second source regions being shallower than that of the first and second trenches, the first and second source regions being provided so as to surround and be close each of the first and second trenches; a first trench-type source electrode buried so as to cover the first trench, a second trench-type source electrode being buried so as to cover the second trench; and a drain electrode provided on a back surface of the semiconductor substrate.