An object of the invention is to obtain a magnetic resonance spectroscopic image to which the MAC summation is applied with high accuracy and in short time, even though a phase characteristic distribution of the MAC has a spatial non-uniformity, in the MRSI measurement using a magnetic resonance imaging apparatus provided with a MAC. Using a non-water-suppressed image signal with high SNR, obtained in the non-water-suppressed measurement (a reference measurement) without water suppression, a correction value for correcting the phase distortion for the MAC summation is calculated on each pixel in each coil. After correcting a phase on each pixel in each coil of a main-scan image signal measured under suppressing water (water-suppressed image signal) using the corrective value, signal adding operation (summation) is performed. Then, a phase correction in a spectrum-axis is to be performed on the summed spectrum signal.