A semiconductor device is provided, including: a semiconductor substrate; a transistor section provided in the semiconductor substrate; and a diode section provided in the semiconductor substrate being adjacent to the transistor section, wherein the diode section includes: a second conductivity-type anode region; a first conductivity-type drift region; a first conductivity-type cathode region; a plurality of dummy trench portions arrayed along a predetermined array direction; a contact portion provided along an extending direction of the plurality of dummy trench portions that is different from the array direction; and a lower-surface side semiconductor region provided directly below a portion of the contact portion at an outer end in the extending direction.