A water hammerless valve includes a pneumatically-operated valve having a valve disc for opening and closing a fluid channel by moving upward and downward through a pneumatic actuator operation, and a limiting mechanism for interfering with upward movement of the valve disc when the water hammer occurs. The limiting mechanism includes a stepping motor including a rotation shaft fixed on the upper actuator; a vertical movement component connected to the rotation shaft for moving upward and downward via rotation of the rotation shaft; a lower detecting component for detecting the fact that the vertical movement component contacts the upper end of a stem when the lower detecting component moves downward; and a control device for rotating the stepping motor, for controlling the air supply, and for transmitting a stop signal to the stepping motor when the lower end of the lower detecting component detects the fact.