This paper proposes a fixed-angle rotor design for a vacuum chamber-free ultracentrifuge using a rigid shaft and magnetic bearings. The rotor is designed for a stable operation in the ultracentrifugation region with air friction. And the optimal design parameters and optimized connection method of the rotor and rigid shaft are proposed. The proposed rotor structure can withstand a maximum rotation speed of 100 000 rpm and achieves a maximum relative centrifugal force of 600 000 g. To verify the performance of the proposed rotor design with a rigid shaft, finite-element analysis, an impact test, and a drive operating experiment were conducted.