A magnetic resonance imaging apparatus and the magnet apparatus thereof comprise plural pairs of magnetic field generation sources, arranged face to face with each other, for forming a magnetic field space 3; and magnetic field homogeneity adjusting apparatuses 17 and 18 for providing homogeneity adjustment of the magnetic field formed in the magnetic field space 3. The magnetic field homogeneity adjusting apparatuses 17 and 18 contain a plurality of tapped holes 24 for installing a magnetic field homogeneity adjusting member 26 of smaller volume in a plate-formed tray made of a non-magnetic substance; and a plurality of mounts 25 for installing the magnetic field homogeneity adjusting member 27 of greater volume, these mounts being formed over the area containing a plurality of through-holes for permitting installation of a magnetic field homogeneity adjusting member 26 of smaller volume, whereby major magnetic field adjusting work can be performed independently of minor magnetic field adjusting work.