A patterned disk medium includes a disk-shaped flat substrate including a
first surface and a second surface located an opposite side of the first
surface. First servo pattern areas including portions provided with
magnetic members and portions provided with no magnetic members are
provided on the first surface. Second servo pattern areas including
portions provided with magnetic members and portions provided with no
magnetic members are provided on the second surface. The magnetic members
of the first and second servo pattern areas are magnetized in a direction
perpendicular to the first and second surfaces. The magnetic polarity of
the surfaces of the magnetic members of the second pattern areas differs
from that of the surfaces of the magnetic members of the first pattern
areas.