A drive device for operating an electromagnetic oscillator includes an OP amplifier for amplifying an analog input signal from an electromagnetic pick-off and an A/D converter for converting an analog signal output from the OP amplifier into a digital signal. The drive device also includes a D/A converter for converting, after digital processing performed by a DSP on the digital signal output from the A/D converter based on phase detection, a digital signal having a processed data amount into an analog signal, and a D/A converter for converting, after the digital processing performed by the DSP on the digital signal output from the D/A converter based on the phase detection, a digital signal having a processed data amount into an analog signal.