PURPOSE: To easily deal with the great increase of the high recording density of a magnetic disk by realizing the low floating amount of a slider without deteriorating the recording/reproducing characteristic of the magnetic head.

CONSTITUTION: This device is provided with a center rail 7 on the center of a slider 2, a skirt part 11 where the rail width D (hereinafter called ABC width D) of the center rail 7 becomes wider as it moves toward the air flow-out groove 6b in an air flowing end area and on other parts the width is made constant. The width of the center rail 7 is made over 200μm on the end surface 15 of an air flowing out end 10b at the skert part 11 and on the areas other than that it is formed at a specified value below 200μm.