An image processing apparatus processes diagnostic image data bearing thereon an image through which a disease is to be diagnosed so that a visible image having a quality optimal to diagnose the disease can be obtained. The image processing apparatus includes an image processing condition storage section and an image processing section. Names of various diseases and image processing conditions for the respective diseases are stored in the image processing condition storage section. The diagnostic image data is input into the image processing section. The name of a disease which is to be diagnosed is input into the image processing condition storage section, and the image processing condition corresponding to the disease is input into the image processing section from the image processing condition storage section. The image processing section carries out image processing on the image data according to the image processing condition input thereinto and generates a processed image data. The processed image data is sent to an image reproducing system where a visible image is reproduced on the basis of the processed image data.