PROBLEM TO BE SOLVED : To create a rental apartment market of a new price range which has never existed in an existing real estate market.SOLUTION : A user accesses an internet server from a user terminal to carry out information acquisition (3) and reservation (4) of a condominium apartment owned by a fund. Reservation reception information (5) and an electronic authentication key are sent (8) from the internet server to the user terminal. Unlocking of the apartment is carried out (10) by an electronic unlocking means supplied to the user by electronic authentication by the portable information terminal of the user. Check out information is sent to a settlement company simultaneously with check out, and a charge is paid from the account of the user (11).COPYRIGHT : (C)2006, JPO&NCIPI