When generating a PET absorption correction image from an MR image, the MR image captured by MRI is divided into regions by pixel values, and the radiation absorption correction value of the region where the linear attenuation coefficient of radiation can be regarded as uniform is the existing radiation absorption correction table. , And the radiation absorption correction value of a region including a plurality of tissues having different radiation attenuation coefficients is obtained with reference to a standard image. This makes it possible to distinguish tissues with the same pixel value but different radiation attenuation coefficients in MR images, and can also be used for individual differences, lesions such as occupational lesions (cancer, abscesses, etc.) and organ defects. A compatible PET absorption correction image is generated.ＭＲ画像からＰＥＴ吸収補正画像を生成する際に、ＭＲＩで撮像したＭＲ画像を、画素値により領域分割し、放射線の線減弱係数が均一とみなせる領域の放射線吸収補正値は既存の放射線吸収補正テーブルを参照し、放射線の減弱係数が異なる複数の組織を含む領域の放射線吸収補正値は標準画像を参照して求める。これにより、ＭＲ画像で画素値が同等であるが放射線の減弱係数が異なる組織を区別することが可能で、個人差や、占拠性病変（癌、膿瘍など）や臓器欠損などの病変部にも対応できるＰＥＴ吸収補正画像を生成する。
