An active matrix substrate includes a substrate and a plurality of oxide semiconductor TFTs supported on the substrate, in which each of oxide semiconductor TFT includes an oxide semiconductor layer including a first region and a second region having a specific resistance lower than a specific resistance of the first region, and a gate electrode disposed on at least a part of the first region with a gate insulating layer interposed therebetween, the gate insulating layer includes a first insulating layer and a second insulating layer disposed on the first insulating layer, and, when viewed from a normal direction of the substrate, the first insulating layer overlaps with the first region and does not overlap with the second region and the second insulating layer overlaps with the first region and at least a part of the second region.