To provide a method for performing an electronic transaction by which the exchange of a commodity and its price can be safely performed through a network and to provide a system device and a recording medium having an electronic transaction program recorded thereon.

In the method for performing the electronic transaction which is the exchange of a commodity and its price between a plurality of seller's devices 1 and a plurality of purchaser's devices 2 through a network 4, a center device 3 adopts a characteristic constitutional procedure for determining a participation charge calculated on the basis of past transaction data as a prerequisite for conducting the transaction and collecting the participation charge from the selling device 1 and the buying device 2.