Triglyceride hydrolysis using lipase has been proposed as a novel method to produce raw materials in food andcosmetic industries such as diacylglycerol, monoacylglycerol, glycerol and fatty acid. In order to design a reactor forutilizing this reaction on industrial scale, constructing a kinetic model is important. Since the substrates are oil andwater, the hydrolysis takes place at oil-water interface. Furthermore, the triglyceride has three ester bonds, so that thehydrolysis stepwise proceeds. Thus, the reaction mechanism is very complicated. The difference between theinterfacial and bulk concentrations of the enzyme, substrates and products, and the interfacial enzymatic reactionmechanism should be considered in the model.