PURPOSE: To obtain the titled compound industrially in high yield with the suppressed formation of by-products, e.g. mono- and diglycrides, etc., by reacting rosin with glycidyl ester thereof in the presence of an organic amine under heating.

CONSTITUTION: Rosin, e.g. gum rosin, wood rosin or hydrogeneated rosin, is reacted with rosin glycidyl ester in the presence of preferably 3W7wt%, based on the rosin, organic amine, preferably a tertiary maine or an onium salt thereof such as triethylamine or tetramethylammonium chloride, by using suitably a solvent having 100W150°C boiling point, e.g. toluene or xylene, in such an amount as to give 50W70wt% solid concentration in the reaction system at 100W150°C for 3W8hr to afford the aimed rosin diglyceride usually in a yield as high as 90% or more.