Optical pickup device and optical disk device including the same

An optical pickup device comprising:

• a light source that emits a light beam toward a recording layer of an optical disk;
• an objective lens that condenses the light beam emitted from the light source onto the recording layer of the optical disk;
• a light receiving element having a plurality of light receiving regions where a returning light beam after being emitted from the light source and reflected on the recording layer of the optical disk is received, each of the light receiving region carrying out output corresponding to the received light intensity and light receiving regions for focusing which are used for focusing servo being formed as part of the plurality of light receiving regions;
• and
• a diffraction element having a plurality of diffraction regions formed by being divided by a division line, each of the diffraction regions diffracting at least part of returning light beams toward the corresponding light receiving region among the plurality of light receiving regions and diffraction regions for focusing which diffract at least part of the returning light beams toward the light receiving regions for focusing being formed as part of the plurality of diffraction regions,
• part of a division line which defines the diffraction region for focusing being formed in a shape which is convex from an outer side toward an inner side with respect to a center of an incidence range on the diffraction element where a returning light beam enters, and
• the part of the division line formed in a shape which is convex from the outer side toward the inner side dividing the incidence range on the diffraction element where a returning light beam enters, regardless of whether or not there is a focus error.