A supporting device is configured to hold and support a portable electronic device. The supporting device includes a main shaft, a plurality of swing arms, a holder, and a plurality of adjustable legs. The portable electronic device is configured to lean against the main shaft. The swing arms are pivotally coupled to two opposite ends of the main shaft and configured to rotate relatively to the main shaft. The holder is configured to receive an edge of the portable electronic device. The swing arms are slidably connected to the holder for adjusting a distance between the main shaft and the holder through the rotating of the swing arms. The adjustable legs are pivotally coupled to the two opposite ends of the main shaft. The adjustable legs are independently movable in at least two degrees of freedom.