To provide a locking apparatus with a simple mechanism capable of minimizing influence to a rotor in structural integrity and stably fixing the rotor to a driving system.

A centrifuge rotor locking apparatus includes a C-shaped annular member 302 for a snap-fit engagement about a drive hub 200. The annular member 302 comprises that first and second contacting segments 310, 312 and a third non-contacting segment 320. Centrifugation causes the contacting segments 310, 312 to flex outwardly and come into contact with the interior wall of the drive hole 12 of a mounted rotor 10. The unbalanced mass distribution of the annular member 302 causes the annular member to tend to slide off the drive hub. This further separates the contacting segments, thus increasing the locking effect of the annular member/drive hub assembly to the rotor 10 as the annular member is wedged in place between the rotor 10 and the drive hub 200.