The authentication printing technique of the invention obtains attachment information regarding attachment of a preset device, such as a hard disk drive, to a printing apparatus. In response to a request for a printing operation with the printing apparatus, the authentication printing technique refers to the obtained attachment information and restricts an authentication printing process according to the attachment information of the preset device. The authentication printing process externally receives print data and prints the received print data on completion of a preset authentication operation. This arrangement effectively reduces the potential for leakage of information from the device attached to the printing apparatus.