This paper describes design and fabrication of a MEMS-based active-head slider using a PZT thin film for flying height control in hard disk drives. A piezoelectric cantilever integrated in an air bearing slider is used to adjust the flying height individually. A novel air bearing surface (ABS) geometry that minimizes the aerodynamic lift force generated beneath the head has been designed on the basis of the molecular gas film lubrication (MGL) theory. The slider with PZT actuator was fabricated monolithically by silicon micromachining. Performance of the actuator was tested by using an optical surface profiler. Furthermore, the fabricated slider was mounted on a suspension and flying height of the slider above a spinning disk has been measured by means of interferometry. Change in the head-disk spacing has been successfully confirmed by applying voltage to the PZT actuator.