An optical head device includes a light source (30) configured to emit a light beam, a light collecting optical system configured to converge the light beam onto an information recording medium (10), a hologram element (20) configured to diffract the light beam reflected from the information recording medium (10), and a photodetector (40) having a plurality of detection regions configured to receive the light beam diffracted by the hologram element (20). The hologram element (20) has two diffraction regions (261 and 262) separated from each other by a straight line (260) extending in a radial direction of the information recording medium (10). At least one of the two diffraction regions has a pattern which introduces coma aberration in the radial direction. The light diffracted by the diffraction region having the coma aberration has coma aberration in the radial direction.