An actuator for liquid ejection which is provided with a plug for closing the ejection spout disposed at the distal portion thereof. This actuator is capable of preventing a residual liquid which is left inside the actuator after an ejection operation from being contacted with an outer atmosphere, thereby preventing the denaturing or degradation of the liquid. Further, it is capable of preventing a ejection spout from being stopped up and of preventing a filmy cover or block to be made. This plug is mounted on an elastic rod-like member disposed in and along the liquid-discharging passage, and is adapted to be moved backward, thus opening the ejection spout as the elastic rod-like member is forced to bend by an actuating rod when the actuator is pushed downward.