PROBLEM TO BE SOLVED : To provide a real estate negotiation system in which marketability and safety of transaction are more strongly pursued in comparison with the conventional real estate auction using the Internet and a real estate negotiation means in a general intermediary market.SOLUTION : In the real estate negotiation system using the Internet, a terminal on the seller' s side and a terminal on the purchaser' s side are connected with a server of a real estate negotiation mechanism via the Internet. The server is provided with : a processing part of real estate desired to be supplied for storing information regarding the real estate desired to be supplied from the terminal on the seller' s side into a data base, and for generating and outputting information about the real estate desired to be supplied; a processing part of real estate desired to be acquired for storing information regarding real estate desired to be acquired from the terminal on the purchaser' s side, and for generating and outputting information about the real estate desired to be acquired; and a generation processing part of real estate use plan information for generating information regarding a possible use plan about the real estate desired to be supplied included in the information about the real estate desired to be supplied, for storing the information in the data base and for outputting it.