An actuator with a safety mechanism includes a gear box (10), a motor (20), a driven gear (30), a transmission (40), a retractable tube (50) and a push switch (60). The transmission (40) has a guiding threaded rod (41) and a touch element (42). When the retractable tube (50) is limited during moving, the transmission (40) will linearly move toward a direction of the retractable tube (50) and the motor (20) is stopped operating by touching the push switch (60) with the touch element (42). Thereby, an anti-pinch effect and increase of safety of using products can be accomplished.