PROBLEM TO BE SOLVED : To solve the following problems : a co-signer is required for renting a room in an apartment or condominium; the residents bear a heavy burden of initial costs such as deposit, premium for lease, and key money; a rental management company is bothered by moving examination that takes a long time and delinquency troubles; renewal is required usually once per two years and the residents have to pay temporary charge; many residents move at the renewal, accordingly; and opportunity losses occur.SOLUTION : A rental supporter having a rent guarantee function and an insurance agency function by credit card payment, is provided to a resident, a real estate management company and a rental property owner related to the rental apartment/rental condominium, to reduce a monetary and time burden and a rent collection risk for rent. The system for reducing the rent according to the residence period is employed to give the resident an advantage (reduction of rent burden) and convenience for the rental property owner (reduction of unoccupied room).COPYRIGHT : (C)2011, JPO&INPIT