1. An image diagnosis supporting device characterized by: digitizing means for applying predetermined image processing to a medical image and generating a multi-valued image comprising discrete multiple values; extracting means for executing at least one decision making processing routine on the multi-valued image generated by the digitizing means and extracting from among shadows a focus candidate shadow, a shadow which is likely to indicate a diseased site; and display means for displaying in the medical image the focus candidate shadow extracted by the extracting means so that it is easily identifiable.