An active device array substrate at least including a substrate, a plurality of pixel units, a plurality of first signal lines, a first connecting wire, a plurality of first switching devices, and a plurality of second signal lines is provided. The pixel units are disposed within an active area. One ends of two neighboring first signal lines are respectively connected to a first test line and a second test line. The other ends of the two neighboring first signal lines are both connected to the first switching devices. Moreover, the first connecting wire is electrically connected to the first switching devices. One ends of two neighboring second signal lines are respectively connected to a third test line and a fourth test line.