A search is performed for information of other products associated with a question about a specific product.A server system 10 searches for information of other products associated with a question about a specific product, in accordance with the following procedure. [1] The server system inputs a product ID and a question text (text) related to a question (S405). [2] The server system extracts a product name corresponding to the product ID from product basic information (FIG. 2(b-1)) in an auction DB 12 (S410). [3] The server system analyzes each of the product name and the question text to specify one or more keywords (S415). [4] The server system sets a search condition for a search for products associated with each specified keyword (S420) and extracts necessary items out of the product information satisfying the search condition, from the product basic information, display information, and product price information (FIGS. 2(b-1) to (b-3)) in the auction DB 12 (S425). [5] The server system outputs the extracted necessary items out of the product information (S430).