HUB FOR DISK-LIKE RECORDING MEDIUM, AND DISK CARTRIDGE

PROBLEM TO BE SOLVED: To surely record/reproduce an information signal by eliminating surface wobbling during the rotation of a magnetic disk having flexibility. SOLUTION: This hub for disk-like recording medium is composed of a disk main body 6 having notched parts 17 to 19 formed in the peripheral edge of a center hole 7, of a disk supporting member 9 including a disk supporting part 13 for supporting a shaft part inserted into the center hole 7 and the peripheral edge part of the center hole 7 of the disk main body 6, and engaging step parts 14 to 16 engaged with the notched parts 17 to 19, and of a supporting member 11 for sandwiching the peripheral edge part of the center hole 7 of the disk main body 6 with the disk supporting member 9, and the hub is further provided with a clamping mechanism 8 for holding the disk main body 6 movably along the shaft part 12, a cartridge main body 4 rotatably housing the disk main body 6, and having recording/reproducing openings 47 and 48 formed to face a part of the disk main body 6 outside, and a center opening 46 formed to face the clamping mechanism 8 outside in the center part of the lower surface side, and stabilizing plate parts 62a and 62b arranged in the inner surface of the cartridge main body 4 to face the disk main body 6.