An imaging device including: a photoelectric converter including first and second electrodes and a conversion layer therebetween; a voltage supplier; an outputter outputting a signal indicating the potential of the second electrode; and a detector detecting the signal level, in which the change rate of the conversion efficiency of the photoelectric converter with respect to a bias voltage, applied between the electrodes, when the bias voltage is in a first range is greater than when the bias voltage is in a second range greater than the first range, and the voltage supplier, when the detected level is less than a first threshold, causes the potential difference between the electrodes to become a first difference, and, when the detected level is greater than or equal to a second threshold greater than or equal to the first threshold, causes the potential difference to become a second difference greater than the first difference.