Provided is a high-quality magnetoresistive thin film by using a method of controlling self bias of a high-frequency sputtering device. In order to control the self bias for the substrate by adjusting a substrate potential, the high-frequency sputtering device according to the present invention includes: a chamber; evacuation means for evacuating the inside of the chamber; gas introduction means for supplying a gas into the chamber; a substrate holder provided with a substrate mounting table; rotation drive means capable of rotating the substrate holder; a sputtering cathode provided with a target mounting table and arranged such that the surface of the target mounting table is non-parallel to the surface of the substrate mounting table; an electrode disposed inside the substrate holder; and a variable impedance mechanism electrically connected to the electrode, for adjusting the substrate potential on the substrate holder.