PROBLEM TO BE SOLVED: To provide a breathing gas heating humidifier capable of enhancing the humidification efficiency of breathing gas.SOLUTION: A chamber 3 of a breathing gas heating humidifier 100 includes: an inlet 41 for taking in a breathing gas in the chamber 3 an outlet 51 for guiding the breathing gas humidified in the chamber 3 to the outside a heating plate 81 heated by a heater 22 and a shee-like humidification member 11 partially soaked by water content in the chamber 3 to keep a humid condition. The sheet-like humidification member 11 is disposes so that it comes in surface contact with the heating plate 81 and allows the breathing gas to circulate along the contacting surface.
