An active device substrate includes a flexible substrate, an inorganic de-bonding layer, and at least one active device. The flexible substrate has a first surface and a second surface opposite to the first surface, wherein the first surface is a flat surface. The inorganic de-bonding layer covers the first surface of the flexible substrate, and the material of the inorganic de-bonding layer is metal, metal oxide or combination thereof. The active device is disposed on or above the second surface of the flexible substrate.