In an air supply apparatus of a fuel cell having a fuel electrode and an air electrode, the air sucked in by an air blower is fed as cooling air to the cooling are passage groove, and a manifold is provided as a communicating member to communicate the exhaust side of a cooling air passage groove with the suction side of a reaction air passage groove (air electrode) such that both cooling air and reaction air are fed to the fuel cell by driving a single air blower. With this, the consumed electricity needed to drive the air supply fan can be reduced, and an increase in the size and weight can be suppressed. In addition, a flow-uniforming device such as current plates, a punching plate or a sponge plate are provided in the manifold.