The present invention provides an RF shimming method for a nuclear magnetic resonance imaging apparatus comprising: a transmission coil having a plurality of channels that respectively transmit high frequencies to an object and a calculation unit performing RF shimming calculation that determines at least one of amplitudes and phases of the high frequencies to be transmitted respectively to a plurality of the channels so as to improve homogeneity of a high-frequency magnetic field distribution generated by the transmission coil and reduce a specific absorption ratio of the object. Objective function parameters for setting the objective function are determined according to contribution to the SAR for each of the channels during the RF shimming calculation based on the objective function and the restriction condition.
