An authentication code detecting unit detects data addition authentication information from a print job. An upper apparatus specifying unit specifies a transmitting source of the print job. A RAM stores the data addition authentication information, the transmitting source of the print job, and the print job. An operating unit receives print request authentication information. An elapsed time measuring unit measures an elapsed time from the reception of the print job having the data addition authentication information. An erasure extension necessity inquiry unit requests an answer about the necessity of extension of an erasing time from the transmitting source when the measurement result indicates the elapse of a predetermined time. When the erasure extension is necessary, an erasure/extension decision processing unit extends the elapsed time until the erasure of the print job after its reception.