A sputtering method with a floating potential cathode has been developed for preparing various films with excellent structure and properties, By setting the magnet behind the target, the applied voltage to the target was lower than that without setting one, The increase of applied voltage was small with increase of discharge current. The plasma shape depended on working Ar pressure. The deposition rate was larger. Accordingly, by setting the magnet behind the target in this method, the method may be useful for depositing Al films at low Ar pressure at high rates.