A supporting device of the invention comprises a main body, a shaft, and a rotating component. The main body comprises a sliding path and an opening. The shaft and the rotating component can slide along the sliding path. The rotating component is connected to the shaft. The shaft and at least a part of the rotating component can then be extended beyond the main body through the opening. Through the aforementioned configuration, the shaft can rotate with respect to the main body when the shaft and at least a part of the rotating component are extended beyond the main body.