A date communication apparatus in which a message stored in advance is transmitted to a receiving station so as to notify the receiving station that a call-waiting signal has been received, if a call-waiting signal is received by a transmitting station during communication. The reception of a request for line connection from a third station is detected by the call-waiting-signal detecting unit of a transmitting station on the basis of the call-waiting signal transmitted by an exchange. If the call-waiting signal is detected, a preset message is read from a message storage unit, and is transmitted to the other station. This message is transmitted either upon completion of the transmission of all the predetermined data or upon completion of the transmission of data, for instance, in units of pages. By means of this message, it is possible for the operator of the receiving station to identify that the cause of the disconnection of the line and the disturbance of the data is due to the reception of the call-waiting signal.