PURPOSE: To prevent a by-product from being generated, to facilitate purification, and to produce lipid countaining a thiol group at a high yield by bringing lipid contng. an amino group on a hydrophilic group side and a thiolacton delivatives into reaction.

CONSTITUTION: The suitable lipid contng. the amino group and the suitable thiolacton delivative are brought into react with the use of triethylamine, for example in a mixed medium consisting of chloroform and a small quantity of methanol. After the reaction, only the component is extracted. Further, it is dehydrated by unhydrous sodium salfate, the crude lipid including the thiol group can be obtained.