Embodiments of the present invention help to stabilize a tilt amount of a head gimbal assembly with respect to a magnetic disc. According to one embodiment of the present invention, in a head stack assembly in which a head gimbal assembly, a carriage, and a head gimbal assembly are stacked and fixed by a pivot cartridge, a spring washer and a nut, an annular recess portion having a length in the radial direction of a flange is formed on a contact face of the flange formed at one end of the cartridge, so that two places of a mount plate of the head gimbal assembly may be partially supported in the radial direction of the flange.