Image processor quantifies a specific biological material in a region of interest of a sample stained with a first staining reagent capable of staining the biological material and stained with a second staining reagent capable of staining a specific region of a cell without interfering with staining with the first staining reagent. A first input means inputs a first image showing the position of expression of the biological material stained with the first staining reagent; a second input means inputs a second image acquired in the same field of view as the first image and shows the morphology of the specific region of the cell stained with the second staining reagent; second image specific region extraction means extracts the specific region from the second image; and derivation means derives the region of interest based on at least the second image undergoing extraction of the specific region among the first and second image.
