Making a promotoin on certain items is a strategy to gain the competitive advantage in retail business. if a customer purchases item A for example, promotoin on item A can be done by giving a bonus of item B, providing discount for item B, or any other form of promotions. at first glance, each kinds of promotion may decrease or even make harm to retail business. to avoid these conditions, the retail entrepreneur must be able to obtain proper information by mining their sales data. information that can be gained is about set of items were purchased usually by customers in conjuction with particular which appears to increase the average profil of that particular item. based on this information, the sales volume of any particular item. based on this information, the sales volume of any particular item may be raised by making the particular item as a promotion item that must be sold together with certain set of items.