PURPOSE: To operate all of a plurality of fuel cells at D.C. current of a uniform value or a specified sharing ratio by controlling at least one of the amount of reformed fuel and air supplied to fuel cells by deviation of mean value per cell or a specified load sharing ratio of the total amount of D.C. current generating from a plurality of fuel cells and d.c. current generating from individual fuel cell.

CONSTITUTION: The amount of D.C. current generating from n units of fuel cells is added with an adder 101. The mean value of generated D.C. current per cell calculated with a divider 102 is inputted to a comparator 103k, a control arithmetic logical unit 30k, and an air amount control arithmetic logical unit 31k. A deviation signal prepared with the comparator 103k is inputted to a control arithmetic logical unit 104k, and a control signal operated with the arithmetic logical unit is calculated with a fuel amount supplement arithmetic logical unit 105k, and an air amount supplement arithmetic logical unit 106k so that the value of D.C. current generated becomes the mean value of D.C. current generated from n units of fuel cells, and added to the control systems of the amount of reformed fuel and air with adders 24k and 107k.