PURPOSE: To reduce a number of constituent parts and man-hour for assembling and to suppress the deviation of the position of a split photodetector due to the difference of linear expansion coefficient by molding the chip of the photodetector putting in a prescribed position when the main body of an optical pickup device is integrally molded.

CONSTITUTION: The main body of the device 1, a collimator lens 4, a reflection prism 5, a condenser lens 6 and a knife edge prism 7 are integraliy molded and, in this case, the split photodetectors 8, 9 are molded by putting the photodetectors in a prescribed position of the main body of the device 1. A light transmission plate 10 is held in a hole 11 so as to rotate around the orthogonal axis to the axis of reflected light incident on the split photodetector 9 and the position of a beam spot incident on the split photodetector 9 is adjusted. Thus, the man-hour for assembling the split photodetectors is reduced and the deviation of position caused by the difference of linear expansion coefficient is removed.