A transmit/receive module that reduces size and weight of a radar apparatus is disclosed. The transmit/receive module includes a transmit input terminal, a receive output terminal, a transmit line, a receive line, and a plurality of branch devices. During monitoring of the transmit line, the plural branch devices are configured so that a standard signal inputted to the transmitting terminal passes through the transmit line, and is outputted to the receive output terminal. During monitoring of the receive line, the plural branch devices are configured so that the standard signal inputted to the transmitting terminal passes through the receive line, and is outputted to the receive output terminal.