An active device array substrate including a substrate, scan lines, data lines, active devices, a first dielectric layer, a common line, a second dielectric layer, a patterned conductive layer, a third dielectric layer, and pixel electrodes is provided. At least a part of the active devices are electrically connected to the scan lines and the data lines. The first dielectric layer covers the scan lines, the data lines and the active devices. The common line is disposed on the first dielectric layer. The second dielectric layer covers the common line and the first dielectric layer. The patterned conductive layer is disposed on the second dielectric layer. The third dielectric layer covers the patterned conductive layer and the second dielectric layer. The pixel electrodes are disposed on the third dielectric layer and electrically connected to the patterned conductive layer and the active devices.