To solve such problems that in a method of producing an alcoholic compound by reducing the ester and epoxide compounds with a hydrogenated boron compound, a generated alcohol is difficult to extract and further, the hydrogenated boron compound having strong reduction power is inferior in handleability and that having weak reduction power is low in reactivity.

In the reduction reaction of the ester and epoxide compounds, the hydrogenated boron compound which is easy to handle but weak in reduction power can be enhanced in that power by using the composition including both hydrogenated boron compound and alcoholic compound in a tetrahydropyran solvent. Besides, since the reaction solvent serves also as the extraction solvent, the simplification of a reaction process as well as energy cost reduction can be achieved. Further, biosafety is enhanced by using tetrahydropyran with low toxicity as the solvent.