This invention relates in general to search and more specifically to two-stage search, where first an incremental character-based search for the keywords and sub keyphrases that together form the target keyphrase to be searched for is performed in order to construct the target keyphrase and then a search for the target keyphrase so constructed is performed among the documents to be searched. The system in this invention is comprised of a user device system from the which the user performs the search, a search server system which performs the search for keywords and sub keyphrases that together form the target keyphrase using text entered by the user and performs the search for documents using the target keyphrase constructed by the user, and an advertisement server system that performs the search for advertisements corresponding to the target keyphrase.