PURPOSE: To relieve a shock for a titled device at the time of starting or stopping operation, by providing a projecting device of a fluid pressure such as oil pressure and air pressure at the end of moving paths of an optical scanning bodies being a moving back and forth body and an original base.

CONSTITUTION: When optical scanning bodies 4, 7 move back and forth, at the same time of seizure of the forth driving a pump 38 is operated so that an oil in a tank 37 is press-transported into a cylinder or the first device A(1) through a valve 39 in an open state, and thereby a piston rod 32 is moved to project. Then, a pressure in a forth moving direction is applied to a rail sliding block 271 of the first mirror supporting base 27 through a lever 35 by the projection of the piston rod 32, and as the result, a positive pressing force becomes an auxiliary initial driving force and even if the optical scanning bodies 4, 7 receive a rapid accelerating force from a driving mechanism owing to the high speed driving, the generation of shock at the starting time on the basis of static inertia is relieved and the oscillation and noise owing to the shock at the starting time are greatly reduced.