A disk drive is realized, which omits running-in for stabilizing a change in a correcting function produced by sliding between balls and a rolling groove in an unbalance correcting mechanism, and prevents immobility and straying of balls, and which comprises a unit mechanism assembled by using 12 balls subjected to surface treatment with heptadecafluorodecyltrimethoxysilane and a turntable plated with a chemical nickel plating containing phosphorus and boron to have a thickness of 5 &mgr;m and by injecting 1 microliter of ester oil into the rolling groove, and further comprises a recess formed in a sidewall of the rolling groove of the unbalance correcting mechanism to prolong the service life of the correcting function.