FUEL CELL MEMBRANE HUMIDIFIER

The present invention relates to a fuel cell membrane humidifier which can actively control the flow rate of exhaust gas flowing from a fuel cell stack according to the output condition of a fuel cell. A fuel cell membrane humidifier according to one embodiment of the present invention comprises: a mid-case having an inlet through which wetting gas supplied from the fuel cell stack is introduced and an outlet through which the wetting gas is discharged; a cartridge disposed inside the mid-case and accommodating a plurality of hollow fiber membranes; a bypass space formed in the space between the mid-case and the cartridge; and an active blocking member for controlling the degree of opening of the bypass space according to the temperature of the wetting gas introduced through the inlet.