1. An image processing device comprising: an interface which inputs a cell shape image showing a shape of a cell in a tissue section and a fluorescence image showing expression of a specific protein as a fluorescent bright point in a region same as a region in the tissue section; and a central processing unit (CPU) which aligns the cell shape image and the fluorescence image based on an information source detected in both the cell shape image and the fluorescence image, wherein the information source is staining information with a certain staining reagent, and the CPU calculates image feature amounts in the cell shape image and the fluorescence image from the staining information on the cell shape image and the staining information on the fluorescence image, respectively, and aligns the cell shape image and the fluorescence image based on the image feature amounts.