PROBLEM TO BE SOLVED : To provide a method for trading without a brokerage commission.SOLUTION : An agent opens a home page only for secondhand houses, which anybody can freely access for free and where anybody can freely notify secondhand houses for free, on a web site of the Internet. Sellers of secondhand houses put information such as pictures of sale objects, desired selling prices, extents of the houses, transfer days, and places of the houses in the home page of the agent. Buyers as persons who desire to purchase secondhand houses put information and conditions such as purchasing prices, places of houses, and extents of houses in the home page of the agent. Buyers make direct contact with sellers of objects, which meet conditions of the buyers, to negotiate with the sellers. After the negotiation between a seller and a buyer results in conclusion of trade, the seller and/or the buyer entrust the agent with procedures, maintenance, and management required after conclusion of trade. The agent performs procedures in place of the seller and the buyer and charges only for a requested case.