PURPOSE : A method for recognizing a fingerprint, and a method for documenting the fingerprint are provided to identify participants' ' information by using a fingerprint data via a specific homepage.CONSTITUTION : When a vendor and purchaser makes a contract, a real estate agent office connects a homepage, and writes a contract for the sale of the property. The homepage transmits contract or the authentication number of the contract note to a touch screen fingerprint reader of a real estate agent' ' s mobile phone. The real estate agent' ' s mobile phone registers the vendor, and the purchaser' ' s fingerprints to the homepage. The registered fingerprints are saved semi-permanently or the specified period. If a contract document is printed, the fingerprints of the contracting parties are printed on the contract document.COPYRIGHT KIPO 2011