A biodegradable in vivo supporting device is disclosed. In one embodiment, a coated stent device includes a biodegradable metal alloy scaffold made from a magnesium alloy, iron alloy, zinc alloy, or combination thereof, and the metal scaffold comprises a plurality of metal struts. The metal struts are at least partially covered with a biodegradable polymer coating. The biodegradable scaffold includes a radio-opaque marker made of a substance that blocks radiation. A cavity is manufactured in the scaffold and the radio-opaque marker is accommodated by the cavity.