PURPOSE: To improve characteristics by steepening the gradient of carrier concentration in the direction of depth of an active layer without increasing internal resistance.

CONSTITUTION: The characteristics of the title transistor is that it is equipped with an active layer 2 consisting of a semiconductor of one conductivity type, a gate electrode 7 to be provided on one surface of the active layer 2 and a Schottky junction with the layer 2 will be formed, a source electrode 8 and a drain electrode 9 where an ohmic connection is formed with the active layer 2 provided leaving the prescribed distance from the gate electrode 7, and an opposite conductivity type region 12 having the other conductivity type consisting of the above-mentioned semiconductor which is the part of the other surface of the active layer 2 and provided on the region opposing to the gate electrode 7.