An active matrix substrate includes a peripheral circuit including a TFT (30A) supported on a substrate (1). When viewed in a direction normal to the substrate (1), a first gate electrode (3) of the TFT (30A) includes a first edge portion and a second edge portion (3e1, 3e2) opposing each other. The first edge portion and the second edge portion extend across an oxide semiconductor layer (7) in a channel width direction. At least one of the first edge portion and the second edge portion includes, in a region overlapping with the oxide semiconductor layer (7), a first recess portion (40) recessed in a channel length direction and a first part (41) adjacent to the first recess portion in the channel width direction. When viewed in the direction normal to the substrate (1), a source electrode (8) or a drain electrode (9) of the TFT (30A) overlaps with at least a part of the first recess portion (40) and at least a part of the first part (41).