NOVELTY - The polymer electrolyte fuel cell has cell having anode, cathode and solid polymer electrolyte membrane, fuel cell stack (18), humidifier (19), fuel gas supply piping (A), oxidizing agent gas supply piping (B), cooling water supply piping (17) and humidification gas supply unit (C). Stack is formed by laminating sheets of cell through separator, and fuel gas and oxidizing agent gas are supplied to anode and cathode, respectively. Humidifier humidifies fuel gas and oxidizing agent gas. Unit (C) supplies fuel gas and oxidizing agent gas with humidity of 100% to stack.    USE - Polymer electrolyte fuel cell.    ADVANTAGE - The polymer electrolyte fuel cell has improved life cycle characteristics, and is economical. The efficiency of electrochemical reaction is improved, since solid polymer electrolyte membrane is maintained to optimal temperature.    DETAILED DESCRIPTION - The polymer electrolyte fuel cell has a cell having anode and cathode on both sides of a solid polymer electrolyte membrane, a fuel cell stack (18), a humidifier (19), a fuel gas supply piping (A), an oxidizing agent gas supply piping (B), a cooling water supply piping (17) and a humidification gas supply unit. The stack is formed by laminating several sheets of cell through a separator, and fuel gas and oxidizing agent gas are supplied to anode and cathode, respectively. The humidifier humidifies fuel gas and oxidizing agent gas with cooling water used for cooling stack. The piping (A) supplies humidified fuel gas from humidifier to stack. The piping (B) supplies humidified oxidizing agent gas from humidifier to stack. The piping (17) supplies cooling water from humidifier to stack. The humidification gas supply unit supplies fuel gas and oxidizing agent gas with humidity of 100% to fuel cell stack.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of polymer type fuel cell. (Drawing includes non-English language text)    Cooling water supply piping (17)    Fuel cell stack (18)    Humidifier (19)    Gas supply piping (20)    Heater (21)    Heater control apparatus (22)