An improved magnetic head assembly is provided by the invention, wherein the upper head device is biased toward the lower head device by a bias means while the lowest position of the upper head device where it comes closest to the lower head device is strictly defined by a stopper means whose position is changeable so that a correct gap is realized between the two head devices. Consequently, even if the upper head device is subjected to adjustment operations to align the upper head to a track while it is under pressure, the upper head device is completely free from any displacement after the adjustment operations and variations of in tracking due to variations in the pressure applied to the magnetic disc by the upper head device.