To discharge appropriately the pure water of a pure water passage at the time of stopping operation.

This is a fuel cell which arranges porous body separators 3, 5 between gas passages 7, 9 and pure water passages 6, 8. The fuel cell comprises opening valves 22, 23 for opening the pure water passages 6, 8 to the drainage passages 20, 21 and furthermore comprises entrance valves 14, 17 and exit valves 14, 17 which are capable of closing completely the passage at the entrance and exit of the gas passages 7, 9 of the fuel cell. The fuel cell is equipped with a control means 30 for closing completely the entrance valves 14, 17 and the exit valves 14, 17 of the gas passages 7, 9 after the pure water passages 6, 8 are opened to the drainage passages 20, 21 at the time of stopping the operation.