A magnetic disk apparatus has a magnetic recording medium including a recording layer formed on a nonmagnetic substrate, and a magnetic head including a magnetoresistive film arranged above the magnetic recording medium and a pair of electrodes formed on both surfaces of the magnetoresistive film along a track direction so as to make a sense current flow in a direction perpendicular to a plane of the magnetoresistive film. The recording layer has an easy axis of magnetization in a direction perpendicular to a track width direction, which is a direction of a magnetic field generated by the flow of the sense current, a ratio M.sub.A/M.sub.e of which recording layer is smaller than 0.6, where M.sub.A is a remanent magnetization in the track width direction and M.sub.e is a remanent magnetization in the direction of the easy axis of magnetization.