Disclosed is an angular rate detection apparatus which provides a stable output with high detection accuracy regardless of a fluctuation of a reference voltage accompanying a fluctuation of a power supply voltage. In one embodiment, a first magnitude of a first polarization signal is measured. It is thus possible to provide a piezoelectric resonator in which, even when noble metal layers are partially removed for increasing adhesion of surface protecting films, exciting electrodes are not brought into an open state between the upper side and the lower side of a piezoelectric resonator piece. An exposure voltage of the photoconductor drum is measured after the image area has been exposed.