A MOS transistor comprises: a first conduction type region; a second conduction type drain region formed on the outermost layer portion of the first conduction type region; a second conduction type source region formed on the outermost layer portion of the first conduction type region with a channel region provided between the second conduction type drain region and the second conduction type source region; agate electrode formed on the channel region; a second conduction type base region formed inside of the second conduction type drain region in plan elevation; a plurality of first conduction type emitter regions formed in the second conduction type base region on the outermost layer portion thereof at spatial intervals in a predetermined direction; and a drain contact connected to, as lying astride, adjacent two first conduction type emitter regions and that portion of the second conduction type drain region between these adjacent two first conduction type emitter regions.