ROTARY ACTUATOR

PROBLEM TO BE SOLVED: To provide a rotary actuator which can be easily controlled.SOLUTION: Operation bodies 11-14 comprising shape-memory alloy 11a-14a, joint bodies 11b-14a and piezoelectric elements 11c-14c are disposed at regular intervals around an output shaft 20. First, a set of opposing operation bodies 11, 12 and a set of opposing operation bodies 13, 14 are operated to approach the output shaft 20 alternately, piezoelectric elements 11c, 12c of the approached set are pushed against a blade 22 of the output shaft 20 to rotate the output shaft 20 and, subsequently, the other set of the piezoelectric elements 13c, 14c are caused to approach the output shaft and are pushed against the blade 22 of the output shaft 20 to rotate the output shaft 20. Thus, one set of shape-memory alloy 11a-14a and the other set of shape-memory alloy are caused to alternately assume a contraction state, and by performing electricity conduction control on the piezoelectric elements 11c to 14c, inner end parts of piezoelectric elements of a set assuming an elongation state are curved to depart from the output shaft to the same direction seen from the outer end sides of the piezoelectric elements and the output shaft 20 is rotated and, therefore, the control is facilitated.