PURPOSE: To control a printer output and to accurately manage data by controlling whether printer printing is to be restarted or not in accordance with the status of a timer means, i.e., its counting period or not.

CONSTITUTION: A printer 21 is connected to a key telephone system having a main device 11 and plural telephone terminals 17a to 17n, 18a to 18n to print out data. When the printing of the printer 21 is aborted, a printer ready signal generated from the printer 21 is temporarily interrupted. When the printer ready signal is restored during the prescribed counting period of a timer means included in a control part 16, the restart of printing is enabled. When the printer ready signal is restored after ending the counting period, the restart of printing is not permitted until a printing request for necessary data is outputted. Thus accurate management can be executed by restarting printing when printer printing is available or waiting the printing until a printable state is set up when the printing is impossible.