When a user wants to set a print density “4”, for example, only to a printer A and not a printer B, the user inputs an input command having a printer specifying command and the print density “4” as a corresponding operating condition, and sends the input command to the printer A via a network to which the printers A and B are connected. When the printer A receives the input command, a discriminating program compares its model number “8” stored in a ROM of the printer A with a model number “8” set in the printer specifying command. If the model numbers match, a setting program sets the print density “4” operation condition.