To separate a water phase from an oil phase well by preventing disperse phase liquid drops from adhering to the inside wall of a mixing tank in separating a dispersion containing a dissolved organic compound in at least either of its water and oil phases.

The dispersion is separated under agitation at a power in the range of 0.002-0.01 kW/m3. Desirably, the dispersion is separated into phases under agitation at a driving force in the range of 0.002-0.005 kW/m3. The difference between the density of the water phase and that of the oil phase is, desirably, at least 0.05 g/cm3, more desirably, at least 0.1 g/cm3.