To provide a printing system capable of erasing surely a confidential data from a storage means of a printer, when a confidential print data is not received normally or erased normally, in the printing system capable of printing a confidential document.

This printing system has the storage means for storing the print data, an analytical means for analyzing the print data stored in the storage means, a printing means for printing the print data, a transmission means for transmitting the print data to the printing means, and a confidential information packet adding means for adding a confidential information packet to the head of the print data to indicate that the print data is confidential information.