A transmitter circuit includes a driver circuit including a non-inverting output terminal and an inverting output terminal for outputting a signal current, which has a loop direction that changes based upon an input signal, to the non-inverting output terminal and the inverting output terminal and an output-waveform control circuit for detecting a waveform edge of the input signal and responding by increasing the signal current temporarily. The output-waveform control circuit includes a first inverter circuit receiving a non-inverted input signal, a first capacitor including one end connected to an output terminal of the first inverter circuit and another end connected to the inverting output terminal, a second inverter circuit receiving an inverted input signal, and a second capacitor including one end connected to an output terminal of the second inverter circuit and another end connected to the non-inverting output terminal.