A humidifier for a fuel cell, the humidifier comprising: a humidification module configured to humidify air supplied from outside using moisture in off-gas discharged from a fuel cell stack; and a cap coupled to one end of the humidification module, wherein the humidification module comprises: a middle case; and two or more cartridges disposed in the middle case, the cartridges comprising a plurality of hollow fiber membranes, and the humidifier further comprises a packing member airtightly coupled to one end of the humidification module through a mechanical assembly method such that the cap fluidly communicates only with the hollow fiber membranes, wherein the packing member comprises: a packing portion having two or more holes into which ends of the cartridges are inserted, respectively; and the packing portion being interposed between the middle case and the cartridges, and an edge portion surrounding the packing portion, the packing portion comprises: a main body including a peripheral portion and at least one rib between the holes; and two or more wing portions respectively surrounding the holes and respectively clinging to the ends of the cartridges inserted into the holes. a humidification module configured to humidify air supplied from outside using moisture in off-gas discharged from a fuel cell stack; and a cap coupled to one end of the humidification module, wherein the humidification module comprises: a middle case; and two or more cartridges disposed in the middle case, the cartridges comprising a plurality of hollow fiber membranes, and the humidifier further comprises a packing member airtightly coupled to one end of the humidification module through a mechanical assembly method such that the cap fluidly communicates only with the hollow fiber membranes, wherein the packing member comprises: a packing portion having two or more holes into which ends of the cartridges are inserted, respectively; and the packing portion being interposed between the middle case and the cartridges, and an edge portion surrounding the packing portion, the packing portion comprises: a main body including a peripheral portion and at least one rib between the holes; and two or more wing portions respectively surrounding the holes and respectively clinging to the ends of the cartridges inserted into the holes. a middle case; and two or more cartridges disposed in the middle case, the cartridges comprising a plurality of hollow fiber membranes, and the humidifier further comprises a packing member airtightly coupled to one end of the humidification module through a mechanical assembly method such that the cap fluidly communicates only with the hollow fiber membranes, wherein the packing member comprises: a packing portion having two or more holes into which ends of the cartridges are inserted, respectively; and the packing portion being interposed between the middle case and the cartridges, and an edge portion surrounding the packing portion, the packing portion comprises: a main body including a peripheral portion and at least one rib between the holes; and two or more wing portions respectively surrounding the holes and respectively clinging to the ends of the cartridges inserted into the holes. a packing portion having two or more holes into which ends of the cartridges are inserted, respectively; and the packing portion being interposed between the middle case and the cartridges, and an edge portion surrounding the packing portion, the packing portion comprises: a main body including a peripheral portion and at least one rib between the holes; and two or more wing portions respectively surrounding the holes and respectively clinging to the ends of the cartridges inserted into the holes. a main body including a peripheral portion and at least one rib between the holes; and two or more wing portions respectively surrounding the holes and respectively clinging to the ends of the cartridges inserted into the holes.