MAGNETIC DISK DEVICE

PURPOSE:To decrease thermal off-track and to reduce a malfunction in the writing and reading of information by forming a spacer ring that laminates a group of magnetic disk with a material having the small coefficient of linear expansion. CONSTITUTION:A spacer ring 10 is made of stainless steel having the coefficient of linear expansion less than half that of aluminum alloy. Thereby, the change of relative height of a magnetic head 5 and a magnetic disk 2 due to the difference of expansion and contraction in axial direction of a spindle 1 caused by temperature difference between the time of recording and reproducing of information, and the change of relative position in the radial direction of the magnetic head 5 and magnetic disk 2, i.e. the quantity of thermal off-track, becomes small, and the malfunction in the recording and reproducing of information can be reduced.