System for humidifying in polymer electrolyte membrane fuel cell

PURPOSE: A humidification system of polymer electrolyte fuel cell is provided to safely supply humidification water to a humidifier through a control of a gas-liquid separator, and to easily control a humidification degree. CONSTITUTION: A humidification system(100) comprises: a stack(110) where fuel gas and oxidation gas are reacted; an anode humidifier(121) moisturizing the fuel gas; and a cathode humidifier(122) humidifying the oxidation gas. In the side of an outlet of a cathode in the stack, a gas-liquid separator(130) is installed. Water separated from the gas-liquid separator is supplied to the anode or cathode humidifier as humidification water. The oxidation gas separated from the gas-liquid separator is supplied to the stack. Water level sensors(131,132,133) are installed in the gas-liquid separator. As the water level sensors detect water level, the humidification water is selectively supplied to the anode humidifier and the anode humidifier. [Reference numerals] (AA, BB, DD, FF) Fuel gas(H2); (CC, EE, GG) Oxidation gas(O2)