Disclosed are: a fuel cell humidifier capable of reliably preventing a gas leak due to repeated operating and stopping of a fuel cell and capable of being manufactured with relatively low manufacturing costs and high productivity; and a manufacturing method therefor. The fuel cell humidifier of the present invention comprises a humidifying module and caps coupled to both ends of the humidifying module, respectively, wherein: the humidifying module includes a mid-case, a plurality of hollow fiber membranes in the mid-case, a fixed layer in which the ends of the hollow fiber membranes are potted, and a composite gasket having a groove into which the end of the mid-case is fitted; the composite gasket includes an inner body, an outer body, and a connecting body provided therebetween and formed of a first material; and at least a portion of the inner body is adhered to the fixed layer and is formed of a second material that is different from the first material.