With minimizing extension of imaging time, the B 1 non-uniformity reducing effect of RF shimming is maximized for an imaging section of an arbitrary axis direction and an arbitrary position. B 1 distributions are measured for only several sections of one predetermined direction, and a radio frequency magnetic field condition that maximizes the B 1 non-uniformity reducing effect for an imaging section of an arbitrary direction and an arbitrary position is calculated from the B 1 distribution data. For example, after B 1 distributions of only several sections of the AX direction are measured, the optimal radio frequency magnetic field condition for an imaging section of an arbitrary position for the AX direction is obtained by interpolation with optimal radio frequency magnetic field conditions calculated from B 1 distributions of two sections near the imaging section, and the optimal radio frequency magnetic field condition for an imaging section of an arbitrary position for the SAG or COR direction is obtained by using only B 1 values of a crossing region with the imaging section extracted from the B 1 distributions.
