Sialocylglycerolipids represented by the following general formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom or a group CH.sub.3 CO--; R.sup.2 represents an alkali metal, a hydrogen atom or a lower alkyl group; R.sup.3 represents a hydrogen atom or a group C.sub.n H.sub.2n+1 -- (n is an integer ranging from 1 to 30); and R.sup.4 represents a group C.sub.m H.sub.2n+1 -- (m is an integer ranging from 1 to 30) are herein disclosed. They are prepared by treating a corresponding compound in an alkaline aqueous solvent. The method makes it possible to provide these compounds in a high yield by a simple processes.