PURPOSE: To obtain 1,4-androstadiene-3,17-dione useful as a raw material for medicines by using an immobilized proliferative microbial cells from microorganisms having the oxidative side chain scission ability for sterols.

CONSTITUTION: To a hydrophilic immobilizing carrier microorganisms having the oxidative side chain scission ability for a sterol selected from among cholesterol, β-sitosterol, campesterol and stigmasterol is stuck and immobilized, and an organic solvent containing said sterol and virtually insoluble or sparingly soluble to water is brought into contact with the immobilized microbial phase on the carrier in the presence of an aqueous medium containing an nutrient for the microorganisms, thus obtaining the objective compound.