To provide a rotary actuator in which a maximum rotational angle exceeding 180° can be attained and a rotor can produce an uniform torque while suppressing fluctuation during variation of the rotational angle.

The rotary actuator comprises an annular yoke 3, a yoke coil 4 wound spirally on the circumferential surface thereof, and a rotor 5 having poles 23, 24 disposed oppositely to the circumferential surface of the annular yoke 3 and rotatable along the circumferential surface of the annular yoke 3. When the yoke coil 4 is conducted, the rotor 5 is rotated through the electromagnetic action of the current and the flux from the poles 23, 24 of the rotor 5. Means 31, 32 for conducting the yoke coil 4 are disposed rotatably along the circumferential surface of the annular yoke 3 and the yoke coil 4 is conducted by rotating the conduction means while following up the rotation of the rotor.