PURPOSE: To expand the range of application of an optical disc memory remarkably by arranging an optical fiber among a light flux converging means, a light source and a light detecting means, moving the optical spot through the moving of the light converging means and the optical fiber only to attain ease of high- speed accessing.

CONSTITUTION: The optical fiber 13 is used to lead light from a light source 7 to an objective lens 2 as a light converging means and to lead a reflected light from the objective lens 2 to a photodetector 5. The optical fiber 13 is formed by bundling plural fibers and made of a polarized plane preserving fiber. Through the above-mentioned constitution, since the optical fiber is flexible, it is possible to move the objective lens 2 independently of other optical system, that is, a λ/4 plate 3, a polarized beam splitter 4, the photodetector 5, a collimator lens 6 and the light source 7. That is, only the objective lens device 14 including the objective lens moving mechanism and the objective lens in the track and focus direction has only to be moved radially.