An adjustment module includes a frame, a sliding member, at least one coiled spring, a pair of guide rails, and a supporting member. The frame includes a main plate. The at least one coiled spring includes an extending portion and a sleeved coiled portion. The guide rails are positioned on opposite sides of the frame. The supporting member is fixed on the frame and has at least one supporting surface. The sliding member is slidably positioned between the guide rails. The coiled portion of the at least one coiled spring is positioned on the at least one supporting surface. An end of the extending portion of the at least one coiled spring is fixed on the sliding member, and an axis of the coiled portion of the at least one coiled spring is substantially perpendicular to the main plate.