A driving mechanism for a massage chair, the massage chair has a primary frame and a massaging set, the primary frame having a vertical bidirectional screw rod, a passive member connected to the massaging set jacketed onto the bidirectional screw rod. The massaging set utilizes the driving motor to provide synchronized massage movements and vertical movements, and the massaging set engages with the passive member and the bidirectional screw rod such that when the massaging set reaches to the very top end or the very bottom end the bidirectional screw rod it directly changes its direction of movement without any sensor, which can reduce and simplify structural costs.