A fuel cell system includes, in an auxiliary device case, a first layer, a second layer and a third layer in order from the end plate side, a coolant discharge pipe arranged in the first layer, cathode-side discharge pipes respectively connected to a plurality of oxygen-containing gas lead-out through holes which interpose the coolant discharge pipe, a plurality of first penetrating portions penetrating the first layer in the thickness direction, and a first connecting part provided in the second layer, extending in the layer direction of the second layer so as to straddle the coolant discharge pipe on the outer side, and connecting the plurality of first penetrating portions.