To provide a technique for alleviating electric field concentration at an end portion and the vicinity of the end portion of the bottom surface of a trench. In a non-active region, a semiconductor device comprises: an outer trench penetrating a third semiconductor layer and a second semiconductor layer to reach a first semiconductor layer, and surrounding an active region; a second insulating film covering the surface of the outer trench; a conductor formed in the outer trench covered by the second insulating film and electrically insulated from a control electrode and a contact electrode; and an outer electrode located outside the outer trench, contacting the second semiconductor layer, and being electrically connected to the contact electrode.