To study the flow separation at the rear end of a 6:1 prolate spheroid, oil flow visualization were conducted on a model in free levitation using the 0.3-m Magnetic Suspension and Balance System. Reynolds number based on the model length was 0.5 million and the angle of attack of the model was set at 0 and 5 degrees. Complicated laminar separation patterns were observed at the rear end of the model even at zero angle of attack. To evaluate the influence of support interference, a systematic experiment was conducted with small excrescences simulating disturbance of a support system. The obtained results indicate that the excrescence has a significant influence on the separation patterns, even when its diameter is as small as 0.5 mm. The separation was delayed in the downstream of the excrescence, suggesting that the change of separation pattern is caused by the transition of laminar boundary layer behind the excrescence.