PURPOSE: To achieve improve reliability of the operation of a fuel cell power generation system by providing it with three pressure detectors used to detect the pressure differences between a fuel, air and an inactive gas and detecting the fault of the pressure detectors.

CONSTITUTION: A power generation system is constituted by installing a fuel cell 1 consisting of a fuel electrode 1a and an air electrode 1b in a case 2 charged with an inactive gas. It is provided with a pressure detectors 3 used to detect the pressure difference (PFN) between an inactive gas and a fuel, a presure detector 4 used to detect the pressure difference (PAN) between the inactive gas and air and a pressure detector 11 used to detect the pressure difference (PFA) between the fuel and air. When a fault occurs in at least one of the detectors 3, 4 and 11, the pressure differences (PFN), (PAN) and (PFA) do not satisfy the relationship PFN=PAN+PFA and signal 13 is generated by a fault-detecting mechanism 12. Consequently, it is possible to improve the reliability of the power generation system by preventing any fault of the fuel cell 1 by detecting the fault of the pressure detectors 3, 4 and 11.