An active device array substrate includes a substrate, an inspection circuit, pixel structures, a passivation layer, and conductive pads. The substrate has a display area and a peripheral area outside the display area. The inspection circuit is located on the substrate and includes inspection switches, inspection control lines, and inspection traces. Each of the inspection switches is located in the peripheral area and controlled by one of the inspection control lines. Each of the inspection traces is connected to one of the inspection switches and includes a first conductive wire segment and a second conductive wire segment. The second conductive wire segment is connected between the first conductive wire segment and one corresponding inspection switch. An electric conductivity of the second conductive wire segment is lower than an electric conductivity of the first conductive wire segment.