In a magnetic disk apparatus, a function of shielding a magnetic head is improved while maintaining the form factor with an inexpensive structure. In one embodiment, a magnetic disk apparatus has a magnetic disk, a magnetic head that records or plays back information, a magnetic head support mechanism supporting the magnetic head, a positioning mechanism that moves the magnetic head in a radial direction of the magnetic disk to place the head in position, an enclosure made of a nonmagnetic material, and a shield member made of a magnetic material. The magnetic disk, magnetic head, magnetic head support mechanism, positioning mechanism, and shield member are housed in the enclosure. The shield member has an upper shield located above the magnetic head and extending over the range of movement of the magnetic head, a lower shield located on the opposite side of the surface where the magnetic head exists and extending over the range of movement of the magnetic head, and a connecting portion connecting an outer side end portion of the upper shield and an outer side end portion of the lower shield near the outer fringes of the magnetic disk.