To reduce a leakage current of a semiconductor device which is equipped with a pn junction exposed on the side of a semiconductor substrate and to enhance its withstand voltage. The semiconductor device is equipped with a semiconductor substrate provided with two main surfaces each having a (111) crystal plane and two or more side faces which have six planes equivalent to the planes of plane orientations (1, -2, 1), a second conductivity-type second semiconductor region of high-impurity concentration which is formed extending from one of the main surfaces into the inside of a first conductivity-type first semiconductor region of low-impurity concentration, a first conductivity-type third semiconductor region which is formed extending from the other main surface into the inside of the first semiconductor region, a first electrode ohmically connected to one of the main surface, and a second electrode ohmically connected to the other main surface. A joint between the second semiconductorregion and the first semiconductor region is exposed on the side face.