Products matching customer wishes are retrieved from among a large variety of merchandise. A topic net in which merchandise features from a customer's perspective are expressed is configured with needs information representing customer needs. Evaluation criteria for topic units are set in the topic net, and based on the needs information with which the topic net is configured, on the evaluation criteria, and on merchandise specifications, a combined suitability level indicating to what extent a product meets the customer's needs is calculated for each product. The product whose combined suitability level is highest may be surmised to be the product most befitting the customer's needs.