The present invention relates to a novel selective synthesis of 9α-hydroxy-steroid derivatives of the general formula (I) (I)—wherein the meaning of -A-A′- is —CH2—CH2— or —CH═CH— group—by the bioconversion of compounds of the general formula (II) (II) wherein the meaning of -A-A′- is —CH2—CH2— or —CH═CH— group—by using Nocardia farcinica bacterium strain, deposition number of which is NCAIM (P)—B 001342, as hydroxylating microorganism in the bioconversion.