Solid oxide fuel cell with sintered air electrode

A fuel cell comprising a fuel electrode and an air electrode disposed on side surfaces of an electrolyte film is disclosed. The fuel electrode is supplied with a fuel gas, and the air electrode is supplied with air. The air electrode has a close-packed structure in which the ratio between the average particle size of coarse particles and the average particle size of fine particles is 5/1 to 250/1. The fuel cell is increased in conductivity.