An optical disc apparatus includes position restricting component for
restricting the position of a unit mechanism portion in a disc plane
direction when the unit mechanism portion is in a raised state. The
position restricting component includes a first portion that restricts
the position of a base of the unit mechanism portion when the base is at
a height position for write or read of information to or from an optical
disc and a second portion that cancels the position restriction on the
base of the unit mechanism portion in the disc plane direction or makes
the position restriction easier than in the first portion when the base
is at a height position corresponding to a chucked portion of the optical
disc onto the turntable. At the height position where the optical disc is
chucked the position restricting component makes the turntable
displaceable in the disc plane direction so that the axis of the
turntable becomes nearly coincident with the center of a center hole
formed in the optical disc.