A geared motor may include a motor and a gear mechanism for transmitting rotation of the motor. The gear mechanism includes an output gear which outputs rotation of the motor and a gear in a preceding stage which is connected with the output gear through another gear and the output gear is formed with a first positioning part showing an angular position of the output gear and the gear in the preceding stage is formed with a second positioning part showing an angular position of the gear in the preceding stage. After an assembling angular position of the output gear and an assembling angular position of the gear in the preceding stage have been determined, another gear is assembled.