A disk drive apparatus includes: an optical pickup irradiating a laser
beam onto an optical disk having one or more recording layers through an
objective lens and receiving the laser beam reflected from the optical
disk; a driving unit moving the objective lens in an optical axial
direction of the laser beam to the optical disk in accordance with a
driving signal; an interlayer distance measuring unit measuring
interlayer distances of a plurality of recording layers of the optical
disk; and a spherical aberration correcting unit obtaining a spherical
aberration correction value for correcting a spherical aberration due to
the objective lens to one of the recording layers of the optical disk. A
spherical aberration correction value to another one of the recording
layers is obtained on the basis of the measured interlayer distances and
the obtained spherical aberration correction value to the one recording
layer.