An imaging unit of an MRI apparatus collects NMR signals using high frequency pulses including a pre-RF pulse exciting a first region and an excitation RF pulse exciting a second region different from the first region. A shimming parameter calculation unit calculating a shimming parameter for adjusting a radiation magnetic field distribution generated by the high-frequency pulses radiated from a plurality of channels sets different shimming parameters in the pre-RF pulse and the excitation RF pulse. The imaging unit performs imaging using the pre-RF pulse and the excitation RF pulse adjusted with the different shimming parameters.