A fuel cell comprising: a membrane electrolyte assembly having a polymer electrolyte membrane and a pair of catalyst electrodes, namely an air electrode and a fuel electrode sandwiching the polymer electrolyte membrane; a pair of separators, namely an air electrode separator and a fuel electrode separator sandwiching the membrane electrolyte assembly; two or more oxidizing gas channels running in a certain direction for the purpose of supplying an oxidizing gas to the air electrode; and two or more linear fuel gas channels arranged parallel to the certain direction for the purpose of supplying a fuel gas to the fuel electrode. Large gaps and small gaps are provided alternately between adjacent two oxidizing gas channels along the certain direction, and the fuel gas channels do not overlap portions of the oxidizing gas channels, that are parallel to the fuel gas channels.