Abstract: This invention has as its object to easily verify alterations etc. of files stored in a folder. To achieve this object, an information processing method of this invention is a method of applying hash processing to files stored in a folder, which includes a designation step of designating a folder; a first generation step (steps S601 and S602) of generating hash data for each of files included in the folder designated in the designation step; a second generation step (steps S603 to S609) of generating one multiplexed hash data by repeating multiplexing each of the hash data generated in the first generation step in turn according to a predetermined order; and a step (step S610) of storing the multiplexed hash data in association with the folder designated in the designation step.