FUEL CELL STACK

In the fuel-cell stack, a bypass channel is formed between the first insulating plate and the second insulating plate. The bypass channel connects the second plate passage to the lower oxygen-containing gas discharge passage. An annular protrusion protruding toward the second plate passage is provided around the first plate passage. A lower part of an inner surface forming the first plate passage has an inclined section that is inclined upward toward the downstream of the reaction gas.