A magnetic head slider includes a magnetic head mounting surface, a slider rail surface, a step air bearing surface, and a negative pressure groove. The magnetic head mounting surface is arranged in a center area with respect to a width of the slider near an air flow-out edge on the slider and mounts a magnetic head. The slider rail surface has a first depth from the magnetic head mounting surface and its width on an air flow-in side for the magnetic head is wider that its width on an air flow-out side for the magnetic head. The step air bearing surface is formed on an air flow-in side of the slider rail surface and has a second depth from the slider rail surface. The negative-pressure groove which formed on an air flow-in side of the step air bearing surface and has a third depth from the step air bearing surface.