This image diagnostic device has a database having associated therein the feature information for each of a plurality of types of stents and the specification information for each of the plurality of types of stents. The image diagnostic device extracts the feature information for specifying a stent, from a stent image inside a blood vessel image, searches the database, and finds the specification information for the stent having feature information having the highest correlation to the extracted feature information. The image diagnostic device then displays, on a display device, an image having added thereto supplementary information for the blood vessel image, on the basis of the found specification information.
