A magnetic recording-reproducing apparatus includes: a magnetic recording medium in which portions corresponding to track portions serve as recording areas and in which portions between the recording areas serve as non-recording areas; and a magnetic head having a main pole and a side shield disposed on both sides of the main pole in a cross-track direction. In the magnetic recording-reproducing apparatus, following inequality (I) is satisfied: S>Tw/2+Gw  (I) where Tw is a track width, Gw is a gap width, and S is a distance between the center of the main pole of the magnetic head and an edge on the main pole side of each of the side shields.