In a magnet system utilizing a pair of magnet bodies each having a cylindrical hollow, by effectively utilizing the hollow spaces of the magnet bodies, the ability of adjusting through magnetic shims the magnetic-field homogeneity of a homogeneous static-magnetic-field space region is enhanced. Two magnet bodies each incorporating a group of superconductive coils and each having a cylindrical hollow are arranged opposing each other; the first ring-shaped magnetic shim is arranged in the cylindrical hollow of the one magnet body, concentrically with the first group of superconductive coils; and the second ring-shaped magnetic shim is arranged inside the first ring-shaped magnetic shim, concentrically with the first group of superconductive coils. Moreover, the third ring-shaped magnetic shim is arranged in the cylindrical hollow of the other magnet body, concentrically with the second group of superconductive coils, and arranged opposing the first ring-shaped magnetic shim; and the fourth ring-shaped magnetic shim is arranged inside the third ring-shaped magnetic shim, concentrically with the second group of superconductive coils, and arranged opposing the second ring-shaped magnetic shim.