To provide a method for producing a thin film which suppresses the frequency of generation of arcing and can suppress the adhesion of foreign matter to a substrate.

The method for producing a thin film includes: arranging a magnet unit 5 including a first magnet 51 having a first polarity on its top face which is opposed to a target 94 and a second magnet 52 which has a second polarity on its top face and is arranged around the first magnet 51, and reducing the closest distance in the Y direction between the outside edge 52a of the magnet unit 5 and the outside edge 94a of the target 94 depending on an increase in the amount of the target 94 used.