PURPOSE: To eliminate the need for a means which combines and adjust the rotray part of a motor and a specular surface by forming a mirror and a rotor for rotational drive in one body, and working the specular surface mirror and the rotor simultaneously.

CONSTITUTION: Bearings 2 and 2' are mounted on upper and lower cases 1 and 1' and a shaft 3 is supported thereupon rotatably. The rotor part α is arranged in the cavity 6 formed of the upper case 1 and lower case 1', and a polygon mirror 5 is fixed 4 by arc welding or adhesion, etc., to the outer circumference of the end part of a rotary support 7 engaged fixedly with the rotating shaft 3. A magnet 9 is attached in contact with an iron ring 8 where magnetic flux is passed, an iron core 10 is fitted and supported on a drooping support part 11 drooping from the upper case 1, and winding 12 connected to an external power source is provided around the iron core 10. The rotor part α is supported on the upper and lower bearings 2 and 2' rotatably around the rotating shaft 3 of the polygon mirror 5, so the angle of deflection of the polygon mirror is decreased.