In an inspection apparatus using nuclear magnetic resonance (NMR), a spatial distribution of homogeneity of a static magnetic field can be quickly measured even when a heterogeneous object is inspected, by measuring simultaneously phase data and a transverse relaxation time at the same spatial position of the heterogeneous object, removing the difference of a phase term due to a chemical shift by anticipating components at that position and obtaining only the phase data resulting from static magnetic field inhomogeneity. A plurality of low-pass filters are provided to a shim power supply unit for driving a shim coil for generating additional static magnetic fields to correct static magnetic field homogeneity so that a low-pass filter having a small time constant is used at the time of adjustment of static magnetic field homogeneity so as quickly adjust static magnetic field homogeneity, and a low-pass filter having a large time constant is used at the time of the actual measurement of the object in order to prevent degradation of S/N of signals.