Abstract: A natural evaporation type humidifier including a sheet-like member provided with a water supply section to supply water to a humidifying section. Because the water supply section immersed in the water is folded up, that portion of the sheet-like member which has a large area is compact in size, and this allows the portion to be immersed in water so as to function as the water supply section. That is, although compactly formed, that portion of the sheet-like member which has the area which is relatively large can function as the water supply section, and as a result, the water supply section has high water supply performance. In contrast to the water supply section, the humidifying section has an expanded shape, so that the humidifying section has a sufficient area for evaporating the water.