PURPOSE: To prevent a shape change due to humidity in atmospheric air or other factors and damage and fouling in the end section of recording paper directly exposed and left to stand in atmospheric air from a recording-paper lot by covering a space, in which the recording-paper lot is housed, in a box shape and driving and controlling a dehumidifying means provided outside.

CONSTITUTION: A box-shaped space is formed by a recording-paper lot inserting mouth 102 at one end and a recording-paper extracting mouth 103 at the other end in a recording paper stocker 101, and a humidity sensor 104 is installed inside. The recording-paper lot inserting mouth 102 is opened to the upper section of the recording paper stocker 101, and a recording paper lot 204 is inserted and mounted. The recording-paper lot inserting mouth 102 keep closed at the normal time except said time. When humidity in atmospheric air is elevated and humidity in the recording paper stocker 101 is also increased, the humidity sensor 104 detects the increase of humidity. The inside of the recording paper stocker 101 is dehumidified before getting subject to a shaped change due to the absorption of humidity in the end of recording paper. Accordingly, dehumidification operation is conducted only at the time required, and a dehumidifying means can be scaled down.