A voltage controller includes: a voltage adjusting unit that controls a voltage controller that changes a voltage of a bus, to which a plurality of power distribution lines are connected, such that the voltage of the bus is within a target voltage range; a communication processing unit that communicates with a voltage controller that controls a voltage control device connected to the power distribution line or a voltage monitoring device that is installed on the power distribution line to measure the voltage at an installation site; a target-voltage-range change request processing unit that transmits a change-possibility confirmation for inquiring about whether the target voltage range can be changed to the voltage monitoring device connected to another power distribution line, via the communication processing unit, and determines whether to change the target voltage range according to a response to the change-possibility confirmation.