Abstract: A current sensor for detecting a current based on a terminal voltage and a resistance value of a shunt resistor, includes: a resistance value correction circuit having: correction resistors; a signal application unit; a voltage detection unit that detects terminal voltages of the shunt resistor and a part of the correction resistors in a first period, and terminal voltages of all of the correction resistors in a second period; and a correction unit that corrects the resistance value for current detection based on a calculated resistance value of the shunt resistor. Resistance values and resistance accuracies of the correction resistors are higher as the plurality of correction resistors are disposed farther from the shunt resistor.

Abstract: A fuel cell system includes a plurality of fuel cell units each including a fuel cell, a fuel cell cooling system having a heat exchanger that exchanges heat between a primary-side coolant, and a secondary-side coolant flowing through the fuel cell, and a coolant pump that adjusts the flow rate of the secondary-side coolant, and a controller that controls the fuel cell, a cooling device, and a cooling system that supplies the primary-side coolant from the cooling device to each fuel cell unit. During stop of operation of the fuel cell system, the cooling device supplies the primary-side coolant having a temperature equal to or higher than a predetermined temperature to each fuel cell unit, and the controller activates the coolant pump to cause the secondary-side coolant to flow through the heat exchanger, in one or more fuel cell units in which the fuel cell has a possibility of freezing.