A search system includes a storage device and a search server. The storage device stores an index database storing an index encrypted with an index key and the index key encrypted with a user key and associated with the encrypted index and stores a document database storing a document encrypted with a document key and the document key encrypted with the user key and associated with the encrypted document. The search server extracts a term for search from a requested search query, decrypts the encrypted index key with a user key which belongs to a user requesting the search query, encrypts the extracted term with the decrypted index key without storing the decrypted index key in a non-transitory storage device, searches the index database with the index encrypted using the encrypted first term, and sends a search result to a terminal.