PURPOSE: To enlarge an erasure rate at an overwrite time by using a recording laser beam and an erasing laser beam where an output wavelength relation is satisfied with a specific condition.

CONSTITUTION: The output wavelength λw of the recording laser beam and the output wavelength λe of the erasing laser beam are selected so as to satisfy the condition of λw<λe. Then, an erasing width becomes wider than a recording width, and the erasure rate at the overwrite time is enlarged. Thus, the remainder of erasure at the time of erasing a recording bit is prevented, and an error rate at a reproducing time is reduced remarkably, and the overwrite of a minute bit is facilitated, and an optical information recorder enhancing reliability and compatibility is obtained.