An active matrix substrate of a liquid crystal display device includes a first substrate, a light blocking layer, a lower insulating layer, a pixel TFT, a source wiring line, a pixel electrode, and a common electrode. The pixel TFT includes an oxide semiconductor layer. The oxide semiconductor layer includes a channel region, and first and second low-resistive regions. The source wiring line is located between the main surface of the first substrate and the lower insulating layer, and is formed from a conductive film the same as the light blocking layer. The pixel electrode is formed from an oxide film the same as the oxide semiconductor layer, and is continuous with the second low-resistive region. The active matrix substrate further includes a connection electrode that is formed from a transparent conductive film the same as the common electrode and connects the source wiring line to the first low-resistive region.