A fuel cell system has: a water supply cycle for supplying water to a fuel cell stack through piping; n numbers of pressure detection devices (n is an even number of two or greater) provided on the piping and detecting pressure of the water; and a control device for determining a pressure anomaly of the water within the piping by comparing a predetermined anomaly determination value to a pressure calculated value obtained by calculation of pressure values detected by the n numbers of pressure detection devices, the calculation including at least addition. In the fuel cell system, if a center point of the piping is divided into n numbers of equal parts by axis lines and one of the axis lines is set as an axis line of a reference pressure detection device, the other pressure detection device is provided within an angle range of .+-.360/2n degrees about the other axis line.