A fuel cell stack includes a plurality of fuel cell modules. Each of the fuel cell modules has a first membrane electrode assembly and a second membrane electrode assembly respectively having an electrolyte membrane and being arranged, such that respective first electrodes are opposed to each other. The fuel cell module also has a first reactive gas flow path arranged to supply a first reactive gas to the first electrodes included in the first membrane electrode assembly and the second membrane electrode assembly, a second reactive gas flow path arranged to supply a second reactive gas to the second electrodes included in the first membrane electrode assembly and the second membrane electrode assembly, and a coolant flow path arranged to cool down the second electrodes included in the first membrane electrode assembly and the second membrane electrode assembly. The fuel cell stack does not have a coolant flow path for cooling down the first electrodes, but has a first flow path-forming member located between the first membrane electrode assembly and the second membrane electrode assembly to define the first reactive gas flow path.