thin-film permanent magnet which is made of a Co - Pt alloy containing 5 - 35 atomic-% of Pt. This thin-film permanent magnet can be readily produced by a sputtering method in which the ultimate pressure before the introduction of a sputtering gas is made 5 x 10 -7 - 1 x 10 -4 Torr. Without any heat treatment, it has a coercivity of 2,000 Oe at the maximum and a remanence of about 8,000 - about 18,000 G.