INFORMATION SEARCH SYSTEM

An information retrieval system is provided to offer the search result optimized for a corresponding user group by grouping users who have the same or similar preference, and then searching information based on the preference of each user group. A server(100) comprises a group generator(110), a group preference generator(120) and a group preference collaborated query generator(130). The group generator produces a spontaneous user group or an involuntary user group. The group preference generator produces the preference specified for each generated group. The group preference collaborated query generator finally generates a group query corresponding to the common interest issue by using the generated preference.