A program generating method acquires a first image set, and retrieves a similar image that is similar to a processing target image included in the first image set, from a database. For each of N number of second image sets in the database, an integrated similarity of an image included in the second image set with respect to the processing target image is calculated based on a first similarity between the image included in the second image set and the processing target image, a second similarity between the second image set and the first image set, and the completeness of the first image set, and the similar image is retrieved based on the integrated similarity.