<p>Waveform data to define a waveform of a modulation wave are stored at a memory of a digital signal generation circuit (251). The digital signal generation circuit (251) outputs a digital signal in accordance with selected waveform data. A DA conversion circuit (252) converts the digital signal to an analog signal to output an original waveform of the modulation wave. The original waveform is amplified by an amplification circuit (255), and a therapy waveform is output.</p>
