To provide a means for realizing ROM/RAM compatibility and low-order compatibility in a recording/reproducing system using a multilayer optical disk or the like having, e.g., 10 layers or more.

First and second laser light source means are included. For the wavelengths of laser beams, the wavelength of a first laser beam for obtaining a reflected light for reproduction and servo and a substantial wavelength for recording, i.e., the wavelength of 1/2 of the wavelength of a second laser beam, are prevented from overlapping each other. The substantial wavelength becomes a wavelength of 1/2 of the wavelength of the first laser beam because the wavelength becomes half in the process of two-photon absorption. Thus, freedom is obtained for setting absorbance and reflectance in the recording layer of a recording medium, i.e., film designing, thereby enabling ROM/RAM compatibility. A land/groove is formed in each recording layer of the recording medium, and the focus positions of the first and second laser beams are roughly matched with each other. Thus, an advantageous configuration is provided regarding the easiness and low-order compatibility of a servo operation.