Abstract: Matrix clustering is defined as a method to obtain sub-matrices with specified area and density for the given sparse binary matrix. This method has been proposed as a data mining technique for customer relationship management and makes it possible to cluster the related items and customers. In this paper, the Apriori algorithm is extended and a new matrix clustering algorithm, which obtains all sub-matrices satisfying some specific condition is proposed. As a result, it is possible to analyze the purchase information of the customers in detail.