A navigator echo is acquired during imaging, and when frequency is corrected based on phase change, the correction is performed with high accuracy without being affected by an offset caused by variations with time. An MRI apparatus including a navigation controller is configured to control an imaging unit acquiring an NMR signal, generate the navigator echo and collect navigation data during a predetermined measurement time, prior to collection of nuclear magnetic resonance signals for reconstructing an image of a subject. The phase change of the navigator echo is analyzed during the measurement time to calculate a correction value for correcting misalignment due to the phase change with a navigation analyzer that calculates a phase change amount relative to a reference, based on a difference between the phase change of the navigator echo and the phase change of the navigator echo serving as the reference during the measurement time.