Electric actuator and actuator device

An electric actuator, comprising:

• a motor part, having a motor shaft that extends in an axial direction and is rotated in both directions;
• a deceleration mechanism that is connected to the motor shaft;
• a circuit board that is electrically connected to the motor part;
• an output part, having an output shaft to which rotation of the motor shaft is transmitted through the deceleration mechanism;
• a sensor magnet that is attached to the motor shaft;
• a motor part sensor that detects a magnetic field of the sensor magnet and detects rotation of the motor shaft;
• and
• a sensor magnet holder which is attached to the motor shaft and to which the sensor magnet is fixed,
• wherein the motor part has a rotor magnet that is fixed to the motor shaft,
• wherein the rotor magnet and the sensor magnet each have a plurality of magnetic poles in a circumferential direction around the motor shaft, and
• wherein the magnetic poles of the rotor magnet and the magnetic poles of the sensor magnet are disposed to be shifted from each other in the circumferential direction;
• wherein the motor shaft has a first positioning part that allows the sensor magnet to be positioned in the circumferential direction with respect to the motor shaft;
• wherein the first positioning part is a recess that is recessed in a radially inward direction from an outer circumferential surface of the motor shaft, and
• wherein the sensor magnet holder has a convex part that is fitted to the recess.