Disclosed is an inverted constant-volume injection mechanism using an actuator which comprises a valve member (5), a movable member (6), a pressing-on operation member (7), and a pressing operation lever (8). On the basis of an operation by a user to hold a container main body and press the pressing-on operation member (7) onto the scalp (13) or a pressing operation by the pressing operation lever (8), first, output valves (5a, 7d) of the actuator are closed and a flow-in valve (4b) of a stem (4) is opened so that the content in the container main body flows into a constant amount chamber (A) defined between the flow-in valve (4b) to the output valves (5a, 7d). On the basis of a releasing operation performed thereafter, the stem (4) returns to a static mode position and the flow-in valve (4b) is closed, so that the content in the constant amount chamber (A) passes through the output valves (5a, 7d) which are opened by the effect of the liquefied gas, and is injected to the external space through a hole (7c) o
