PURPOSE: To make the construction of the actuator in the title compact, by putting a piston rod into a rotary shaft and also fixing a bracket on the rotary shaft.

CONSTITUTION: A shaft cylinder 19 is formed at one end of a rotor shaft 10, and a piston rod 18 is fitted into the shaft cylinder 19. A bracket 35 is fixed on the rotor shaft 10 at the same end as the one where the shaft cylinder 19 is located, and the bracket 35 is so fixed that it is stopped by coming into contact with a piston rod 30 when the piston rod 30 is protruded. Due to the above construction, an oscillating mechanism, a linear moving mechanism, and a midway-stopping mechanism can be integrated into one compact unit, which can be conveniently used in various ways without costing any undue space.