A fuel cell system is capable of shifting to a normal operation quickly, and can be provided in transportation equipment such as a motorbike. The fuel cell system includes a cell stack which has a plurality of fuel cells; an aqueous solution tank which holds aqueous methanol solution to be supplied to the cell stack; a water pump which supplies water to the aqueous solution tank; an electric current detection circuit which detects an electric current value of the cell stack; and CPU which controls the fuel cell system. The CPU drives the water pump, and thereby starts a liquid amount adjustment if the electric current value detected by the electric current detection circuit becomes not lower than a predetermined value after power generation of the cell stack is started.