In a voltage monitoring system, a voltage monitoring module includes an adjusting current control circuit to generate an adjusting current so that the operating current consumed by the voltage monitoring modules reaches a specified value corresponding to a first operation current setting command, and stops generating the adjusting current according to an operating current switching command; and an operating current measurement circuit to measure the operating current according to the operating current measuring command following the operating current switching command; and in which a module control circuit sends a second operation current setting command based on the operating current that was measured, and the adjusting current control circuit generates an adjusting current so that the operating current reaches a specified value corresponding to the second operating current setting command.