To also ensure confidentiality of a person who signs, while ensuring confidentiality of document data.

A signature request device is provided with a ring information operation part 205 which generates ring information with respect to signature generation devices from document data of a signing object, public information of the signature generation devices, and random numbers, and generates ring information with respect to dummy signature generation devices from the document data of a signing object, public information of each dummy signature generation device, and random numbers; a ring information blind section 206 which applies blind processing to both pieces of ring information to generate blinded ring information; an input/output section 209 which transmits the blinded ring information to the signature generation devices, and receives the blinded signature information from the signature generation devices; and a signature information blind removing section 207 for finding signature information being blinded signature information to which blind removal processing has been applied, and the device outputs document data with a signature comprising the signature information, the document data being a signing object, and the public information of the signature generation devices and the dummy signature generation devices.