To provide a method for purchasing a commodity of an extremely high customer satisfaction degree by acquiring information other than determinate commodity information when purchasing a commodity requiring high-degree or technical knowledge, a commodity having wide range service use, or a commodity having many similar articles when a customer purchases the commodity at a virtual store in an electronic commerce system via the Internet.

The customer inputs a question item of a non-routine form when purchasing the commodity, and can acquire an answer for taking a position of using the commodity and an answer containing comparison information with a similar commodity to the question item from a specialist, and can purchase the commodity of the extremely high customer satisfaction degree. The function is provided for storing and retrieving the question item and the answer of the customer and the specialist in a knowledge base. By the function, the answer can be speedily acquired by avoiding duplicate communication between the customer and the specialist. Convenience is imparted to the customer by arranging the stored knowledge base, and adding and displaying an item having a high frequency at any time. As a result, the commodity of the high customer satisfaction degree can be purchased.