An objective lens of this embodiment is used in an optical head in which a
distance between a DVD laser and a CD laser is fixed. The objective lens
focuses a laser beam emitted from the DVD laser on a DVD by a numerical
aperture of 0.60, and focuses a laser beam emitted from the CD laser on a
CD by an numerical aperture of 0.47. The wavefront aberration in design
for CD is set greater than the wavefront aberration in design for DVD.