The present invention seeks, when a temporary abnormality occurs in a voltage converter, a recovery of the voltage converter, and minimizes the inadequacy of the drive power. In a fuel cell system comprising an electric storage device disposed with a voltage converter, in the case where an abnormality occurs in the voltage converter, the voltage converter is stopped once, an attempt is made to recover the voltage converter to a normal state after the voltage converter is stopped, and drive power is generated in at least a fuel cell until the voltage converter recovers to the normal state. It is preferred that an upper limit of the power which can be generated when the voltage converter recovers to the normal state be set to a value lower than an upper limit of power obtained prior to the occurrence of the abnormality. Further, it is preferred that the limit be canceled step by step when recovering the voltage converter to a normal state.