Described herein is a hard disk drive HDD which adopts a CSS type floating or levitation head device. A condensation sensor is provided on the inner surface of a housing or chassis. Since the capacity of the chassis is large and moisture adsorbed by the chassis due to dew condensation or the like is hard to dry, the condensation or the like produced on the inner surface side of the chassis can be detected accurately by placing the condensation sensor on the inner surface of the chassis. The condensation sensor may be attached to an arm or suspension constituting an actuator, a head slider, a flexible printed board, or a portion or the like formed of the same material as that for a magnetic disc. When the condensation or the like is detected by the condensation sensor, the magnetic disc is allowed to stand by in a state of remaining stopped rotating until it is not detected. Thus, damage to the magnetic disc and breakage of the head slider or the like due to their sticking can be previously prevented from occurring. Owing to the above construction, high humidity or condensation can be effectively detected and damage to a recording medium and breakage of the head slider or the like can be prevented satisfactorily.