To provide a rotary actuator for which nearly consistent torque characteristics with neither decline in rotating torque nor uneven torque can be assured without increasing the size and weight of the entire body by suppressing magnetic saturation in the latter half process of rotation within an operation angle range.

In the latter half process of rotation wherein a plate magnet 8 reaches a stop position L from an initial position H and magnetic saturation easily occurs, a magnetic flux from an auxiliary magnet 11 acts on a magnetic flux from a coil body 3 and a magnetic flux from magnetic pole planes 8a-8d to demagnetize them. In the latter half process of rotation of the plate magnet 8, magnetic saturation is suppressed and thereby there arises no decline in rotating torque. Nearly consistent rotating torque characteristics having neither decline in rotating torque nor uneven torque, therefore, is secured within a predetermined operation angle range α. An auxiliary magnet 11 is downsized, as provided between adjacent segment core portions 9, so that the whole body is built in a simple and light-weight configuration.

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