PURPOSE: To improve the follow-up characteristics of a magnetic head to rock of a magnetic disk and make the off-track extent much less than before by bringing the back surface of a gimbals spring in surface contact with a spring specifying surface formed on a base, and thus specifying the flection of the gimbals spring which is more than prescribed.

CONSTITUTION: When a magnetic disk 14 is straight as usual, the gimbals spring 12 is brought into contact with the spring specifying surface 10 and a spring support surface 9 is set about 0.3mm higher than the spring specifying surface 10, so that the 2nd magnetic head 13 follows up undulations of the magnetic disk without placing any load on the disk. Further, the spring support surface 9 and spring specifying surface 10 are varied in height according to the specification of a machine to improve the follow-up characteristics. For example, the support spring surface 9 is set about 0.2mm and the spring specifying surface 10 is set about 0.5mm higher than the surface of the magnetic disk 14 in the normal state to follow up about 1mm rocking.