An MRI apparatus and method reduces eddy currents generated by changing gradient magnetic fields used to image an object. Positioning image data from a pilot imaging mode is used to set reference imaging conditions for a subsequent actual diagnostic imaging mode used to acquire diagnostic image data. An eddy current stimulus index is calculated for a gradient magnetic field polarity successively (i.e., iteratively) renewed (i.e., changed) by renewal of imaging conditions and phase-encoding direction. Diagnostic image data is generated during an actual diagnostic imaging mode based on a gradient magnetic field polarity and phase-encoding direction that provides the lowest eddy current stimulus index value, thus using an optimum set of imaging conditions.