PURPOSE: To make unnecessary the spacer and to make easy the handling and chucking, by making thicker the thickness of the handling section mounted on the spindle hub than the thickness of the disc.

CONSTITUTION: The underneath nonspacer disc 6 is placed on the spindle hub 3, next the 2nd disc is directly overlaid without spacer, and the uppermost part is fixed to the spindle hub 3 with the clamp 4. The clamp 6a of the disc 6 mounted to the spindle hub 3 is protruded more upward and downward than the thickness of the disc 6. Thus, the distinction between the magnetic recording surface and the clamp section 6a is easy, the spacer is made unnecessary with the thickness, the chucking by mechanical work is made easy and the roundness and accuracy toward vertical direction can be increased.