An identifier (232) identifies an alternative product to an attended product getting attention from a user. A searcher (231) searches, when a search condition is given, a group of products satisfying the search condition. A first generator (233) generates a first search condition expected to obtain a search result containing the attended product and the alternative product. A verifier (234) verifies, based on an obtained first search result by the searcher (231) that has searched under the generated first condition, whether or not the first search condition is proper. A second generator (235) generates a second search condition that is the first search condition verified as proper and with an added or replaced condition of a price range that is different from a price range of the attended product. A presenter (240) presents an obtained second search result to the user by the searcher (231) that has searched under the generated second condition.