A head arm assembly comprises a slider, a drive arm, a trace; and a load beam having a hinge portion and a slider mounting portion; wherein the slider mounting portion has a slider support portion to support flying attitude of the slider. The slider support portion has a slider mounting frame with a flexible lifter to maintain the slider position in a predetermined position. In the present invention, the flexible lifter has a spring structure. The load beam may further comprise a stiffener formed in a longitudinal direction of the head arm assembly. The invention also discloses a head stack assembly and a disk drive using the head arm assembly.