To provide a spring return-type electric actuator capable of surely relieving the impact force in returning by a spring, having a long life without failure, and being inexpensively manufactured with a simple structure.

In this spring return-type electric actuator wherein an output shaft 2 is rotatably mounted on a motor 3 through a train of gears 8, on the other hand, the output shaft 2 is backwardly rotated by the accumulated force of the spring 4 wound up by the motor 3, a disc 20 unrotatably mounted on the output shaft 2, and an output gear 22 rotatably mounted on the output shaft 2 are mounted in a state of being interlockable with each other in both directions through a locking part 23 formed on the disc 20, and the locking part 23 runs idle in a circular arc-shaped hole part 25 formed on the output gear 22 in stopping the rotation of the output shaft 2 in spring return.