PURPOSE: To obtain an optical scanner which is safe and can prevent destruction of the photoelectric transducer, by constituting the unit so that the scanning head may be placed in the light shielding part off from the transparent plate, where a scanned face is put and fixed, at the time other than moving of the scanning head.

CONSTITUTION: In the holding state of scanning before optical scanning start, scanning head 22 is always so set that it may be placed under light shielding part 25 off from transparent plate 24 where an original is put. Therefore, in the course of scanning operations, original 12 and transparent plte 24 have all surfaces covered with original shielding cover 26, and the irradiated laser beam cannot leak to the external; and in the holding state of scanning head 22 before scanning start or after scanning end, the laser beam cannot leak to the external even if original shielding cover 26 is removed. Further, since no light invades directly photoelectric transducers 22b and 22c from the external, they can be prevented from being destructed by intensive energy of the external light.