As apparel manufacturers have increased their outsourcing garment making to cope with the rapid changing market, the information sharing has been the most important factor for the Korean apparel industry. The purpose of this research was to identify the properties and effects of information sharing system between Korean apparel manufactures and contractors. For this study, two apparel manufactures which actually used the information sharing systems were case-studied for the properties and effects of the information sharing system. The results of this study are shown as follows; 1) The companies ("J" and "S"), studied in this paper used sharing information mostly on order, delivery, and accounts within their contractors based on information sharing system. Company "J" turned out to have strong partnership with their contractors and developed more flexible manufacturing system and QR strategy. They shared not only basic transaction information but also quality inspection information and work-in-process information by using information sharing system. 2) The effects of information sharing system were proved as business transaction time reduced more than 60 percent, compared when staffs had to face to face, or use phone or fax to deliver documents. This study was investigated to provide an example which introduces information sharing system objectively and systematically to the apparel industry.