Provided is an image processor including a tissue-segmentation-processing-unit that performs tissue segmentation processing on at least one of a plurality of complex images generated based on a magnetic resonance signal generated from a subject to calculate a tissue-image related to a predetermined specific tissue, a magnetic-susceptibility-image-calculation-unit that calculates a magnetic-susceptibility-image showing magnetic susceptibility of a predetermined tissue included in the complex image from the complex image, an anatomical-standardization-processing-unit that calculates a standard-magnetic-susceptibility-image and a spatially-normalized tissue-image by performing spatially normalization processing on the magnetic-susceptibility-image and the tissue-image and calculates a volume modulated spatially-normalized tissue-image obtained by performing volume modulation on the spatially-normalized tissue-image, a magnetic-susceptibility-calculation-unit that calculates magnetic susceptibility of the specific tissue based on the spatially-normalized -magnetic-susceptibility-image and the spatially-normalized tissue-image, and a diagnostic-index-calculation-unit that calculates a diagnostic index for diagnosing a predetermined disease based on the magnetic susceptibility of the specific tissue and the volume modulated spatially-normalized tissue-image.
