A search technique having enhanced ease-of-use is provided. A search server analyzes web contents, extracts index information (e.g., time, geographical name, personal name, and business type), and registers the index information in an index information database. A time information search unit performs search using time as a key, a geographical name information search unit performs search using a geographical name as a key, a personal name information search unit performs search using a personal name as a key, a business type information search unit performs search using a business type as a key, and a topic information search unit performs search using a topic as a key. In order to perform narrowing down search while using these search engines integrally, a federated search unit provides a user interface to specify combined search conditions for the search engines.