A method for isolating biologically active substance from raw material of vegetable origin includes isolation of biologically active substance by an electric vacuum condensing unit comprising a vacuum chamber with at least one sealing lid, a control unit of heating, a control unit of vacuum pump and a control unit of cooling device. Isolation of a biologically active substance is carried out by drying the plant material under the temperature from 35 °C to 41 °C in rarefied air in the vacuum chamber with a pressure from 0.3 kg/cm2 to 0.7 kg/cm2 and condensation of vapors generated during drying. This drying plant material is carried out using heating elements and by blowing a layer of this material by vapors formed during drying in the vacuum chamber with at least one fan.