A field effect transistor comprises: a semiconductor substrate; a semiconductor layer provided on the semiconductor substrate, the semiconductor layer including a body region which contains an impurity of a first conductivity type; a gate dielectric film provided on the semiconductor layer; a gate electrode provided on the gate dielectric film; and a source region and a drain region provided in the semiconductor layer at positions below the sides of the gate electrode, the source region and the drain region containing an impurity of a second conductivity type. The gate electrode and the body region are electrically short-circuited. In the semiconductor layer except for the source region and the drain region, at least part of a junction portion bordering on the source region or the drain region contains the impurity of the first conductivity type with a higher concentration than in the body region except for junction portions bordering on the source region and the drain region.