Active matrix substrate and demultiplexer circuit

An active matrix substrate includes a demultiplexer circuit which includes multiple TFTs. Each TFT includes a gate electrode, an oxide semiconductor layer that includes a source contact area, a drain contact area, and an area between a source and a drain that includes a channel region, a channel protection layer that covers only a portion of the area between the source and the drain, a source electrode that is brought into contact with the source contact area, and a drain electrode that is brought into contact with the drain contact area. At a cross-section in a channel length direction, of each TFT, an end portion facing toward the channel region, of one of the source and drain electrodes is brought into contact with the channel protection layer, and an end portion facing toward the channel region, of the other is positioned at a distance away from the channel protection layer.