OPTICAL PICKUP DEVICE CAPABLE OF STABLY DETECTING ERROR SIGNAL

PROBLEM TO BE SOLVED: To obtain an optical pickup device capable of stably detecting an error signal. SOLUTION: A signal detection unit is adopted, which includes a hologram member 10 with a plurality of pattern regions for diffracting and/or condensing light reflected by a record medium for entering, a photo detector 30 with a plurality of light reception regions for receiving light diffracted by the hologram member 10 for photoelectric conversion, and a signal operation part 50 for generating a focus error signal and/or a track error signal from the detection signal of the photo detector 30. The signal detection unit can stable achieve servo embodiment even in the case of the distortion of the photo detector 30, the change in light wavelength being emitted from the light source, and/or the shifting of a condensing means such as an objective lens, thus recording and/or reproducing information to and/or from the record medium with a high density.