Rocket turbopump is representative of a high-speed and high-power turbomachinery that has often suffered from rotor vibration problems. It is important to elucidate the effect of rotordynamic fluid forces generated from shaft seals on the rotor vibration. The purpose of this study is to clarify and to compare with rotordynamic characteristics of various seals and the impact of this force on rotor vibration. Experiments to measure the rotordynamic characteristics of the seals were conducted by using the rotordynamic test stand in JAXA (JARTS) with active magnetic bearings.According to the result of comparison of the seals, the floating ring seal and the segment seal have high direct damping C, low cross-coupled stiffness k and high effective damping C eff . These non-contacting seals have positive influence for stability of the rotor at wide range of whirling velocity of a rotor.