PURPOSE: To obtain a continuous magnetic thin film medium having no wave even when it is fabricated under a high sputtering power by maintaining a constant tension in a film, stretched over a ring, against expansion/contraction thereof through springs arranged on the both sides of the ring.

CONSTITUTION: CoCr particles are sputtered from a CoCr target onto a polymer film arranged in a chamber 7 to form a magnetic thin film. In order to stretch the film even if it is expanded due to temperature rise, a push-in amount control knob 11 for lifting/lowering the ring is fixed through springs 9, 10 to a substrate holder 1. The film is loosened at the time of film formation, but when the spring constant of the spring 9 is set higher than that of the spring 10 the spring 9 imparts higher force than the spring 10 and thereby the spring 9 pushes up a link 3 by an amount corresponding to thermal expansion of the film thus contracting the spring 10. Consequently, the film is continuously stretched resulting in a vertical medium having no waving.