PURPOSE: To reduce the communication cost by shortening line connection time when requesting print-out through a communication network to an output terminal.

CONSTITUTION: When a command for printing processing is transmitted from a center 3 to an output terminal 4, the output terminal 4 starts the printing processing, returns a response to the center 3 before the end of printing processing and disconnects a line. Therefore, the center disconnects the line without the response of normal printing end. The printed result is added to the response and transmitted to the center 3 in the following communication between the center 3 and the output terminal 4. The center 3 can also positively request a response to printing processing in the past to the output terminal 4.