A polymer electrolyte fuel cell comprising a first separators for oxidizing gas and a second separator for fuel gas and a membrane/electrode assembly sandwiched between the separators. A first group of oxidizing gas flow passages flowing, from an entrance towards a turning point, has the longer length than a second group of oxidizing gas flow passages. The second group of flow passages, from the turning point towards an exit, are formed on the plane of the first separator. A downstream of the flow passages of the first group is located near an upper stream of the flow passages of the second. The flow passages of the first group and flow passages of the second group adjoin one another on the plane of the first separator.