An optical system for optical pickup, which optical system is used for performing recording, reproducing, and/or erasing of information on an optical recording medium and has a simple configuration, is provided. An optical pickup device 1 includes a collimator lens system 23, a beam expander 33, and an objective lens system 34 that includes an S-SIL element 27b. The beam expander 33 includes a lens element 33c that is supported so as to be movable in a direction perpendicular to an optical axis. By moving the lens element 33c in the direction perpendicular to the optical axis, a coma aberration of a spot on a recording layer can be compensated in a state where the interval between a surface of an optical recording medium 28 and the S-SIL element 27b opposed thereto is maintained constant.