A method for separating and enriching isotopes in an efficient and low-cost manner from a condensation-system (liquid or/and solid) material including two or more different isotopes by taking advantage of the sedimentation of atoms through an acceleration field by ultra-high speed rotation. The condensation-system material is placed in a sedimentation tank which is then housed in a supercentrifuge. The supercentrifuge in its rotor is rotation driven by an ultra-high speed rotation power source, and an acceleration field of energy of 100000 G to 1500000 G, i.e., about 100 to 800 m/s in terms of peripheral velocity, is applied to the above condensed (liquid or/and solid) material under such a temperature that is specified by an isotope material to be enriched. In this case, a difference in centrifugal force applied is provided between the isotopes in the condensed (liquid or/and solid) material comprising the at least two isotopes. By virtue of sedimentation by taking advantage of this difference, isotope atoms within the condensed material interact, and, consequently, separation and enrichment of the isotopes can be realized in a higher efficiency than the case where gas is used, by conducting the separation and enrichment of the isotopes within the liquid material, using an effective material, and using a multistaged rotor system.