An adjusting device comprising a foot member, a supporting member, and a moving member. The supporting member is fixed to the foot member, and the moving member includes at least a moving body, an elastic device and a button. The moving body includes two passageways, one of which is sized to receive the supporting member so that the moving body can move vertically and is coupled to the supporting member, and the other of which is sized to receive the elastic device so that the elasticity of the elastic device embeds in the passageway horizontally to clip to the supporting member so that the moving body is fixed to the supporting member. The button is movable horizontally or vertically and is buckled to the moving body, through which the user can impose a force horizontally or vertically to deform the elastic device, so that the elastic device can disengage from the supporting member for the adjustment.