This semiconductor device (100) includes: a gate electrode (3); a gate insulating layer (4); an oxide layer (50) which is formed on the gate insulating layer (4) and which includes a first conductor region (55) and a first semiconductor region (51) that overlaps at least partially with the gate electrode (3) with the gate insulating layer (4) interposed between them; a source electrode (6s) formed to contact with the upper surface of the first semiconductor region (51) of the oxide layer (50); a drain electrode (6d) which is formed to contact with the upper surface of the first semiconductor region (51) of the oxide layer (50) and which is electrically connected to the first conductor region (55); and a conductive layer (60) which is formed in contact with the upper surface of the oxide layer (50) and which a plurality of holes (66) or notches. The oxide layer (50) has a plurality of second conductor regions (57, 58), and each of which has a surface exposed inside respective one of the holes or notches of the conductive layer.