A supporting device is disclosed, which comprises a support; a slider including at least one self-lubricating block; a pressing block disposed at the second opening, abutting the inner side of the second opening, and fixed on the slider so that the slider may tightly abut against the support through the self-lubricating block; and an elastic element disposed between the support and the slider. When a force is applied to the slider, the slider may move between a highest position and a lowest position with respect to the support while the self-lubricating block rubs the support. When the force is removed, the slider may stop at any vertical height with respect to the support.