A fuel cell humidifier may completely or substantially completely prevent condensate water from entering a running fuel cell stack. The fuel cell humidifier includes a housing; a plurality of hollow fiber membranes arranged in the housing; a cap which is coupled to one end of the housing and has an air discharge port for supplying humidified air to the fuel cell stack; and a bypass tube for transferring condensate water generated from the humidified air to an interior space of the housing through which a discharge gas flows, wherein a first end of the bypass tube is disposed inside the air discharge port, and the bypass tube is in fluid communication with the interior space of the housing through a second end of the bypass tube.