The optical miniaturized module includes a semiconductor laser for irradiating an optical disk with laser light, a diffraction grating for forming a main beam and two sub beams from the laser light, a polarization hologram for dividing reflected light from the optical disk, and a photodetector for detecting the reflected light. The polarization hologram includes a first parting line defined in a direction optically corresponding to a radial direction as the optical disk rotates. A main beam M incident area is divided with a boundary defined by the first parting line. A sub beam A incident area and a sub beam B incident area are each arranged avoiding the first parting line.