A semiconductor device includes a semiconductor layer located between first and second electrodes. The contact location of the semiconductor layer with the first electrode forms a first contact plane. The semiconductor layer includes a first-conductivity-type first semiconductor region in contact with the first electrode, a second-conductivity-type second semiconductor region located between the first electrode and the first semiconductor region and contacting the first electrode, a second-conductivity-type third semiconductor region located between the first electrode and the second semiconductor region and contacting the first electrode and having a higher impurity concentration than that of the second semiconductor region, and a second-conductivity-type fourth semiconductor region located between the first electrode and the first semiconductor region and contacting the first electrode. The fourth semiconductor region is narrower than the second semiconductor region, shallower than the second semiconductor region, and has a lower impurity concentration than that of the third semiconductor region.