Provided is a hard disk drive device that can be formed in a small size, which is capable of maintaining the humidity inside the device to the initial manufacture humidity for a long term and capable of adjusting the difference between the pressures of the inside and outside the device. The hard disk drive device includes: a casing formed by an upper housing and a lower housing; and a magnetic disk as well as a magnetic head housed inside the casing. An intake port for adjusting a difference between pressures of inside and outside the casing is provided to the upper housing or the lower housing, and the intake port is sealed by a pressure-adjusting gel-type member from outer side. Further, the pressure-adjusting gel-type member is formed substantially in the same size as the aperture size of the intake port.