A semiconductor device (1001) includes: a thin film transistor (101) including an oxide semiconductor layer (16) including a channel region, and a source contact region and a drain contact region arranged on opposite sides of the channel region; an insulating layer arranged so as to cover the oxide semiconductor layer (16), the insulating layer having a contact hole (CH) through which the drain contact region is exposed; and a transparent electrode (24) to be in contact with the drain contact region in the contact hole (CH), wherein: as seen from a direction normal to the substrate, at least a part R of the drain contact region overlaps a gate electrode (12); and on an arbitrary cross section that extends in a channel width direction across the at least part (R) of the drain contact region, a width of the oxide semiconductor layer (16) is greater than a width of the gate electrode (12), and the gate electrode (12) is covered by the oxide semiconductor layer (16) with the gate insulating layer therebetween.