To provide a vibration drive voltage automatic gain control circuit of microgyroscope.

This invention ensures stable quantity owing to maintaining always constant sensitivity regardless of temperature change by providing an automatic gain control circuit controlling drive voltage in vibration direction based on the voltage corresponding to displacement change of a microgyroscope 10, automatically controlling the gain of direct current bias voltage of the direct current voltage of the drive voltage against the temperature change and maintaining constant the displacement in the vibration direction even with temperature change.