A head slider is designed to prevent collision against a surface of a disk due to an external impact and the like while a device is in use to avoid damages on an air bearing surface ("ABS") of the head slider and the surface the disk. This is achieved by a structure of the head slider which produces a large positive pressure on a positive dynamic pressure generating section when the head slider comes close to the disk. More specifically, the ABS of the head slider comprises three surfaces of different positional heights, and the positive dynamic pressure generating section having a height equivalent to a mid level surface of the second highest position is provided on a portion of the head slider made of a material of high brittleness at each of locations near both side edges lateral to a tracking width of a magnetic head. In addition, a head mounting pad bearing the magnetic head is so configured that a boundary between a high level surface in the highest position and a mid level surface is asymmetrical with respect to the lateral center of the head slider in a direction of the tracking width of the magnetic head.