PROBLEM TO BE SOLVED : To stably gain a rental income from building real estate such as a flat while reducing a fund for purchase.SOLUTION : This real estate investment system used in management of the real estate for investment is provided with a storage device 13 storing information about a plurality of real estate properties, a computer 11 connected to the storage device for controlling the real estate property information, and an input/output device 13 connected to the computer. In investment in the real estate property according to the real estate information, the computer finds an equity of the investor as a priority equity on the basis of a previously decided sharing ratio when the input/output device inputs that sharing of the investment real estate property is desired by an investor and a real estate agent, and as to the priority equity, the computer calculates a guaranteed dividend amount according to a previously decided yield. If loan is required, the computer calculates a loanable fund on the basis of a total of the real estate agent' s equity and the investor' s equity.