The Johnson-Furter equation, which correlates the salt effects on relative volatility changes of components in a binary mixture at presence of salt, is extended to salting-out phase separation phenomenon observed in aqueous solutions of some water-miscible organic solvents. The extended equation quantitatively correlates partitions of components of the ternary mixture, namely, the organic solvent, water, and the salt between the salted-out two phases, and is successfully applied to five ternary mixtures including acetonitrile-H 2 O-LiCl, -NaCl, -KCl, acetone-H 2 O-NaCl, and 2-propanol-H 2 O-NaCl where salting-out phase separation occurs. A molecular mechanism of salting-out phase separation as salt-solvent and solvent-solvent interactions is also discussed by using Kirkwood-Buff solution theory.