A housing includes an opening portion, which opens in one direction. At the time of assembling, the opening portion of the housing is placed to face an upper side. Then, a wave washer, an electric motor and screws for motor fixation are assembled from the upper side, and a first intermediate shaft and a second intermediate shaft are press-fitted, and a lower bearing, an output shaft, a second intermediate gear, a first intermediate gear are assembled. Thereafter, a cover is installed from the upper side to the housing. Next, an actuator lever is connected to a distal end part of the output shaft. As discussed above, the electric actuator can be assembled without inverting an orientation of the housing, and thereby productivity can be improved.