An optical servo magnetic head in which the rigidity in a slider is maintained, and a servo error due to dust particles is suppressed. In a separate type magnetic head (1) generally composed of a slider (2) and a back yoke (3), the slider (2) is provided with magnetic cores (11 and 12) for standard recording density and high recording density, respectively, in order to cover, with a single unit of magnetic head, a plurality of recording media having respective recording densities different from each other. A laser beam is used to guide the magnetic head to a prescribed track position, and passage-holes (5 and 6) for permitting the laser beam to pass through are formed through the slider (2) and the back yoke (3), respectively, by molding or machining. Since the passage-holes (5 and 6) can be respectively set to a minimal size required for permitting the laser beam to pass through, it is possible to maintain rigidity in the slider (2) and prevent fine dust particles generated due to the sliding between the recording medium and a sliding surface of the magnetic head from falling through the passage-holes.