Air breather with waterproof fiber material for magnetic disk drive

Embodiments in accordance with the present invention provide a magnetic disk drive that reliably prevents entry of water or other form of liquid through a breathing hole for the enhanced performance, reliability, and the like. In one embodiment, a box body forming part of a hard disk drive (HDD) has a top cover. The top cover includes a breathing hole drilled therein. The breathing hole serves to eliminate any pressure difference between an inside and an outside of the HDD. A fiber waterproof body, which includes a waterproof fiber material or the like, is fitted in a large-diameter hole of the breathing hole. A pore waterproof body, formed by bundling up a large number of slender pores, is mounted in a small-diameter hole of the breathing hole.