A superconducting magnet device for magnetic resonance imaging, which has an opening wide enough to prevent the examinee from feeling confined and to enable the operator to have easy access to the examinee, wherein magnetic leakage is reduced. The superconducting magnet device is provided with two sets of superconducting coils opposed across a uniform magnetic field are. The return circuit of external magnetic fluxes generated by the superconducting coils is constituted by arranging discoid ferromagnetic bodies and cylindrical ferromagnetic bodies around the superconducting coils and a plurality of columnar ferromagnetic bodies between the facing cylindrical ferromagnetic bodies. Therefore, the magnet device can have an opening wide enough to prevent the examinee from feeling confined and to enable the operator to have easy access to the examinee. This device causes less magnetic leakage while the manufacturing cost is low.