A magnetic disc device includes a moisture removing mechanism within an enclosure of the device. The mechanism employs a reversible desiccating agent which is capable of not only absorbing moisture but also discharging moisture depending on the surrounding conditions. The reversible desiccating agent cyclically absorbs and discharges moisture in response to a change in temperature and a change in humidity due to the intrusion of the moisture from outside the enclosure. The moisture removing mechanism can be used for a long period of time with a small amount of desiccating agent. Thus, it is possible to make the moisture removing mechanism small and to provide it with long life.