An electric actuator configured to convert a rotary motion generated through drive by a motor into a linear motion in a direction parallel to an output shaft of the motor to output the linear motion, the electric actuator comprising: the motor ; and a motion conversion mechanism configured to convert a rotary motion generated through drive by the motor into a linear motion in a direction parallel to the output shaft of the motor , a sensor target, comprising a magnet and a magnet holder configured to hold the magnet a moveable part , to which the sensor target is mounted through fitting and which is arranged in parallel with the output shaft and is configured to perform the linear motion; and a magnetic sensor , which is arranged around the movable part , and is configured to detect a position of the magnet ; characterised in that one pair or a plurality of pairs of fitting claws capable of being fitted to an outer peripheral surface of the movable part are formed on the magnet holder ; and in that the magnet holder further comprises a fitting recessed portion , which is formed on an opposite side of a protruding side of the fitting claws , and is configured to receive the magnet fitted therein; wherein the fitting recessed portion comprises a pair of side wall portions ; a first sandwiching portion , which is formed integrally with the pair of side wall portions ; and a second sandwiching portion , which is formed independently of the pair of side wall portions and the first sandwiching portion , and is capable of sandwiching the magnet together with the first sandwiching portion . the motor ; and a motion conversion mechanism configured to convert a rotary motion generated through drive by the motor into a linear motion in a direction parallel to the output shaft of the motor , a sensor target, comprising a magnet and a magnet holder configured to hold the magnet a moveable part , to which the sensor target is mounted through fitting and which is arranged in parallel with the output shaft and is configured to perform the linear motion; and a magnetic sensor , which is arranged around the movable part , and is configured to detect a position of the magnet ; characterised in that one pair or a plurality of pairs of fitting claws capable of being fitted to an outer peripheral surface of the movable part are formed on the magnet holder ; and in that the magnet holder further comprises a fitting recessed portion , which is formed on an opposite side of a protruding side of the fitting claws , and is configured to receive the magnet fitted therein; wherein the fitting recessed portion comprises a pair of side wall portions ; a first sandwiching portion , which is formed integrally with the pair of side wall portions ; and a second sandwiching portion , which is formed independently of the pair of side wall portions and the first sandwiching portion , and is capable of sandwiching the magnet together with the first sandwiching portion . a pair of side wall portions ; a first sandwiching portion , which is formed integrally with the pair of side wall portions ; and a second sandwiching portion , which is formed independently of the pair of side wall portions and the first sandwiching portion , and is capable of sandwiching the magnet together with the first sandwiching portion . <EOS>