In a server; a ticket allotting unit generates, in response to a first request from a first user, first-type image code and stores the first-type information in a management database (DB) in a manner corresponding to a second user. Moreover, in response to a second request from the first user, generates second-type image code which is different from the first-type image code and stores the second-type image code in the management DB in a manner corresponding to a third user. Then, for example, a QR returning unit invalidates the first-type information stored in the management DB and validates the second-type information stored in the management DB. Then, a QR displaying unit sends the second-type image code to the third user.
