To provide a method for preparing a lipid from a lipid precursor that is hydrophobic with an extremely high lipid yield.

The method for preparing a lipid (A) from a lipid precursor (a) using a microorganism is characterized by comprising causing a lipid precursor (a) having been made soluble to a culture medium by a surfactant (B) to contact with a microorganism in the culture medium. In particular, the surfactant (B) is comprised of one or more of anionic surfactants containing a sulfur atom selected from the group consisting of an alkylsulfate comprising a 8-24C alkyl group and an alkylsulfonic acid salt.