A magnet unit, which can realize uniform film thickness distribution of a thin film formed on a substrate without increasing the length and width of a target. The magnet unit includes a peripheral magnet, which is disposed on the yoke on the back side of a cathode electrode so as to follow the outline of a target, and an inner magnet disposed in the peripheral magnet and having a polarity different from the polarity of the peripheral magnet. The magnet unit provides a magnetic track MT that is a set of regions which tangents of magnetic field lines M generated on the target parallels to the target surface. The magnet unit further includes n (n is a positive integer of two or more) extending magnetic pole portions and n−1 projecting magnetic pole portions, which form 2n−1 folded shape portions U at the both ends in the longitudinal direction of the magnetic track.