The present invention is intended to provide a method for preparing a Eucalyptus extract that is capable of decreasing a Eucalyptus specific odor and also obtaining an effective ingredient in high purity and high yield as a physiologically active ingredient. An essential oil constituent is removed from a Eucalyptus plant and the residue is extracted with water or an organic solvent aqueous solution and then the obtained extraction residue is further extracted with an organic solvent aqueous solution or an organic solvent, whereby Macrocarpal A, Macrocarpal B and Macrocarpal C contained in the Eucalyptus as a physiological active substance are prepared in higher content than using a conventional method and the extract having good taste, appearance and properties is prepared.本發明係提供減少桉樹特有的臭味，可高純度且高產率得到作為生理活性物質之有效成份之桉樹萃取物的調製方法。藉由自桉樹屬植物去除精油成份，以水或有機溶劑水溶液萃取該殘渣，將所得的萃取殘渣，再以有機溶劑水溶液或有機溶劑萃取，調製比傳統的萃取方法更高含量之桉樹中所含生理活性物質之大果桉醛(macrocarpal)A、B及C，調製呈味或外觀、物性面上良好的萃取物。
