PROBLEM TO BE SOLVED : To provide a dealings support method, a dealings support system, a dealings support equipment, a computer program thereof, and a recording medium thereof which support persons who are involved in the dealer to grasp the value of the dealing object exactly and to determine the validity about the dealings when they perform a dealing such as buying, selling, exchange or rental, etc., of the dealing objects such as real estate, etc.SOLUTION : This system, while opening a dealings object 200 such as real estate and information in relation to the dealings object 200 to the public through communication network such as Internet, etc., opens an investigation trustee such as an investigation enterprise 300, etc., which performs the investigation of the dealings object 200 and the consulting such as advices, etc., based on the investigation and information in relation to the investigation trustee to the public.