NOVELTY - The humidifier has a humidification tank (201) for storing water. A gas introduction pipe (204) introduces gas into an inner side of the humidification tank, and is provided with a gas outlet port (206). A cylindrical shaped heating apparatus (202) is arranged in an inner side of the humidification tank, and heats the water. An opening part of the gas outlet port is arranged at a lower part of the heating apparatus such that the heating apparatus is extended toward an upper surface of the humidification tank. Gas bubble blows-off from the gas outlet port.    USE - Humidifier for supplying humidification gas to a fuel cell i.e. solid polymer electrolyte-type fuel cell (PEFC), that is utilized as a power supply of a base station i.e. domestic-use cogeneration system, a motor vehicle and a mobile telephone. Can also be used for supplying humidification gas to a pharmaceutical storage cabinet, a semiconductor component storage cabinet, an art work storage cabinet and an expiration re-production evaluation apparatus during humidification of metal-fume-fever process, ceramic firing heat process, fiber printing process and static removal in powder and granulation process in a factory.    ADVANTAGE - The opening part of the gas outlet port is arranged at the lower part of the heating apparatus such that the heating apparatus is extended toward the upper surface of the humidification tank, so that the water in the tank can be efficiently heated, temperature fall of the heating water can be prevented, temperature distribution can be made uniform, humidification state can be ensured, humidification efficiency can be improved, foam bonding can be prevented an dew point precision can be improved.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of a humidifier. '(Drawing includes non-English language text)'    Humidification tank (201)    Cylindrical shaped heating apparatus (202)    Gas introduction pipe (204)    Gas outlet port (206)    Central direction (211)