In imaging analysis of a living body, a Region Of Interest (ROI) is set on the basis of the state of radiopharmaceutical accumulation. An example for setting an ROI includes: performing first transformation for anatomically standardizing, with the use of a positive template, a nuclear medicine image acquired by applying a radiopharmaceutical to a subject; performing second transformation for anatomically standardizing, with the use of a negative template, the nuclear medicine image; calculating a degree of similarity between a first anatomical standardization image acquired by the first transformation and the positive template; calculating a degree of similarity between a second anatomical standardization image acquired by the second transformation and the negative template; and applying, to an ROI template, inverse transformation of the first transformation or the second transformation, whichever has the higher of the calculated degrees of similarity, in order to set the ROI.