A two-way communication CATV system has a CATV broadcasting station, a relay device, and a plurality of CATV terminal devices. The CATV terminal device in the two-way communication CATV system includes a storing device for storing a recognition number, a frequency determining device for determining the frequency of a broadcasting signal transmitted from the relay device, and a recognition number setting device for determining a recognition number depending on the frequency determined by the frequency determining device and storing the determined recognition number in the storing device.