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.