In order to synthesize a sugar ester at high concentration, 1,2-O-isopropylidene-alpha-d-glucofuranose (IpGlc), which is one of the sugar acetals and is more hydrophobic than unmodified glucose, was esterified with palmitic acid at 40A degrees C using immobilized lipase from Candida antarctica in some organic solvents or their mixtures. Acetone + t-butyl alcohol (3:1 v/v) improved both the initial reaction rate and yield after 80 h: the product reached its maximum value (240 mmol/kg solvent; ca. 110 g/kg solvent) when 400 mmol IpGlc/kg solvent and 1,200 mmol palmitic acid/kg solvent were used in this solvent mixture.