[PROBLEMS] can be suppressed that the steam is generated by dew condensation water is mixed in the air, to provide a humidifier that can control the humidity of the air in a stable condition.
[MEANS FOR SOLVING PROBLEMS] humidifier 5 of the present invention, extending along the a and, the storage tank 51 for storing water, open toward the top, the heater 52 for heating the water in the storage tank 51, the horizontal in a first direction (D1) which is, with respect to the center of the storage tank 51 has a guide plate 53 placed on top of the storage tank (51) in at least one of one side and the other side. The guide plate 53, that extend obliquely upper portion is positioned at the center side of the storage tank (51) in a first direction (D1) than the lower portion. A humidifier (5) is provided in the horizontal flow passage of the air tube passage of the air conditioner. The horizontal passage portion, the downstream-side opening is provided, the downstream-side opening is mounted on the plate is passed through the air holes formed. And a humidifier (5), the second direction (D2) perpendicular to the first direction (D1) on a horizontal plane, and arranged along the extending direction of the horizontal flow path, also in the case of this along the second direction (D2), the part of the guide plate 53 is disposed to overlap with the air passage holes.