PURPOSE: To precisely monitor a communication fee by accumulating the communication fee announced from a network for the unit of an arbitrary user and displaying a message/inhibiting following transmission as needed when the communication fee exceeds a communication limit fee set in advance.

CONSTITUTION: The transmission limit fee and information to show whether the transmission is inhibited or not are set in a fee control table 6-1 of a non- volatile memory 6 in advance corresponding to the arbitrary user unit, and when the transmission is started and the transmission flag of the fee control table 6-1 shows inhibiting the transmission, the message is displayed so as to inhibit the transmission. On the other hand, when the transmission is not inhibited, the transmission is executed and concerning the communication fee announced from the network at the end, the accumulated fee for the unit of the arbitrary user in the fee control table 6-1 is updated. When the updated accumulated fee exceeds the transmission limit fee and it is set in advance to inhibit the transmission, the transmission flag is set to inhibit the transmission. Thus, the communication fee can be precisely monitored.