PURPOSE: To absorb an impact of the time when a scanning direction is converted, by crossing a wire through other pulley, when winding a wire to a pulley provided on the second mirror scanner, and decelerating a scanning speed before converting the scanning direction.

CONSTITUTION: When winding a wire 16 around a pulley P1' of the second mirror scanner 15, the wire 16 is crossed through other pulley P7. As a result, as P1' and P7 approach each other, a winding angle θ of the wire 16 to the pulleys P1', P7 increases, therefore, a brake action is generated in the second mirror scanner 15, and it is decelerated together with the first mirror device 14 interlocking with it. Also, as the winding angle θ of the wire 16 increases, the wire 16 becomes tight, a spring 18 of its other end 16b is stretched, and a damper effect is increased. According to such constitution, an impact of the time when the scanning direction is converted can be absorbed by decelerating a scanning speed before converting the scanning direction.