A supporting device for supporting a display is provided. The supporting device includes an upright, a slider, a bearing module, a driving module, a transfer module, and a control module. The slider is slidably disposed in the upright, and partially extending outward from the upright. The bearing module includes a bearing board and a supporting element. The bearing board bears the display, and the supporting element is connected to the slider. The transfer module is connected between the driving module and the bearing board. The control module is electrically connected to the driving module, and controls the driving module to drive the transfer module to make the bearing board rotate about the normal axis and relative to the supporting element, and the display changes between a portrait state and a landscape state.