1. A magnetic resonance imaging device comprising: a static magnetic field generation part for generating a static magnetic field in a space in which a subject is placed, an irradiation part for irradiating a radio frequency magnetic field pulse on the subject, a reception part for receiving magnetic resonance signals generated from the subject by irradiation of the radio frequency magnetic field pulse, a gradient magnetic field application part for applying a gradient magnetic field for imparting spatial information to the magnetic resonance signals, a control part for operating the irradiation part, the gradient magnetic field application part, and the reception part according to a predetermined pulse sequence to perform imaging with two different echo times, and an image reconstruction part for reconstructing original images from the magnetic resonance signals obtained with the two different echo times, which further comprises: a phase difference map calculation part for calculating phase difference maps induced by inhomogeneity of the static magnetic field from the original images, a phase-corrected image calculation part for calculating a phase-corrected image by carrying out phase correction of one of the original images using the phase difference map, and a water/fat separation image calculation part for calculating a water/fat separation image from two images, the phase corrected image and the original image not subjected to the phase correction.