PROBLEM TO BE SOLVED : To solve the following problem of a conventional rental contract : guarantee related to quality of residential behavior in a form wherein troublesome action to a neighbor resident is not caused is not considered at all though guarantee that a person is a superior renter with respect to payment of rent is considered. SOLUTION : In this person guarantee system, the person desiring rental of a real estate is guaranteed by use of a person index that is a new index considering not only money paying capacity but also a personality of the person. The person guarantee system has a function calculating a guarantee condition exhibited to the rental applicant by a third party when the third party gives the personal guarantee of the rental applicant to a lender on the basis of the person index. COPYRIGHT : (C)2007, JPO&INPIT