An active device array substrate including a substrate, a plurality of semiconductor patterns, a gate insulator layer, a first patterned conductive layer, a dielectric layer, a plurality of transparent electrodes, a passivation layer, and a second patterned conductive layer is provided. The semiconductor patterns are disposed on the substrate. The gate insulator layer is disposed on the substrate to cover the semiconductor patterns. The first patterned conductive layer disposed on the gate insulator layer includes a plurality of scan lines, a plurality of gate electrodes disposed on each semiconductor pattern and connected with the scan lines, and a plurality of common electrodes disposed between the scan lines. The dielectric layer is disposed on the gate insulator layer to cover the first patterned conductive layer. The transparent electrodes are disposed on the dielectric layer. The passivation layer is disposed on parts of the dielectric layer to expose the transparent electrodes.