This study was carried out to determine the optimum conditions for water-in-oil-in-water (W/O/W) micro-encapsulated lactase (beta-galactosidase) in order to prevent the intolerance of lactose in milk. The core material was lactase and the coating materials were medium-chain triglyceride for W/O phase, and whey protein isolate (WPI), maltodextrin, gum arabic, and its mixtures for W/O/W phase. Polyglycerol polyricinoleate (PGPR) was used as a primary emulsifier, and polyoxyethylene sorbitan monolaurate (PSML) was selected as a secondary emulsifier based on emulsion stability index. To determine the most efficient conditions for the W/O/W-lactase microencapsulation, the ratio of core to coating materials and amounts of emulsifiers were investigated by response surface methodology. The optimum ratio of core to coating materials in W/O, amount of PGPR, ratio of core to coating material in W/O/W, and amount of PSML were found to be 0.5-9.5, 0.75% (w/v), 1.7-8.3, and 0.25% (w/v), respectively. The average size of the microcapsules was about 10 mm under optimum conditions. Microcapsules of 30% (w/v) WPI as a secondary coating material could evenly distribute the pocket of lactase. Based on the data obtained from this study, lactase microcapsules could effectively be produced by the method of W/O/W double emulsion.