To improve convenience of a user in a service providing system etc.

A print data management unit 32 uniquely produces an indication key and an indication key with control right, and to hold and manage after corresponding to a confidential document when the confidential document is newly received. A key notification unit 33 notifies two kinds of data identification keys to a document source. When a document is intended to be added to a transmitted document stored in a complex machine 20, the indication key with the control right which is notified relating to transmission of the document and addition indicating information are transmitted after being added to the document which is to be added. A print data management unit 32 stores the document sent to the document which is defined by the indication key with the control right when the addition of the indication key with the control right and the addition indicating information to the received document are recognized. At this time, the indication key and the indication key with the control right is uniquely produced, held, and managed by making correspondence to stored additional documents, then a key notification unit 33 notifies the data identification key to the document source. At a time of execution of printing, the additional document is printed by inputting the indication key responding to the additional document from a complex machine 20.