A transmission device transmits differential signals that are to be output, in the form of current signals via first and second output terminals. A first switching transistor and a first output transistor are serially connected between the grounded terminal, which is set to a fixed electric potential, and the first output terminal. A second switching transistor and a second output transistor are serially connected between the grounded terminal and the second output terminal. First and second bias transistors are provided in parallel with the first and second switching transistors, and generate a predetermined bias current. A pair of differential signals, which are to be transmitted, are input to the gates of the first and second switching transistors. The gates of the first and second output transistors are biased at a predetermined first voltage.