A fuel cell system to be mounted on an electric vehicle such as a hybrid vehicle or an electric vehicle. Cooling water is supplied from a cooling water inlet of a stack manifold, flows through a fuel cell stack, and returns to the stack manifold. A groove is formed on the rear surface side of the stack manifold, constituting, together with a terminal, a cooling water channel. The cooling water flows through the cooling water channel, and is discharged to the outside from a cooling water outlet. The cooling water channel is formed extending from the rear side to the front side of the vehicle, and warms an end plate. A pipe length of the cooling water channel to a radiator mounted in a front part of the vehicle is reduced.