A rental real property converting method for seniors includes the steps of (a) executing a preliminary sale agreement between the seniors as conditional purchasers and a seller of the rental real property; (b) converting apartments of the rental real property into a plurality of condominium properties that a sole ownership of the rental real property is converted into multiple ownerships for sale units, wherein a market value of each of the condominium properties must be higher than a sale price of the corresponding to apartment of the rental real property; and (c) selling the condominium property to the respective conditional purchaser, wherein an amount of the “reverse mortgage” loan, in responsive to the market value of the respective condominium property, is pre-arranged for paying off the corresponding apartment of the rental real property at the sale price thereof and a conversion cost of the corresponding apartment.