To provide a technique for reducing interlayer noises without using any special additional member.
The optical disk driving device is provided with: a light source for outputting light of a predetermined wavelength; a photodetector for detecting reflected light reflected on one of information recording layers of a recording medium which includes at least two information recording layers provided with one of first recording density and second recording density higher than the first recording density, a lens for condensing the light from the light source so as to exhibit a smallest spot in one of the information recording layers of the recording medium; and a signal processing circuit for obtaining, among reflected light rays detected by the photodetector, a component of the information recording layer other than that exhibiting the smallest spot to change a lens position.
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TAZAKI YOSHINORI
SUGIYAMA KAZUMI
