An electronic business transaction system is provided. The electronic business transaction system requests an ordering party to select an electronic business and input order information for the electronic business through a terminal of the ordering party, receives the order information for the electronic business from the ordering party, announces a bid for the electronic business, requests bidders to select the electronic business, input bid information for the electronic business, and organize execution groups for the electronic business through a terminal of the bidders, receives the bid information and information for the execution groups from the bidders, analyzes the bid information and the information for the execution groups, selects an order-taking party from among the bidders according to the results of the analysis, concludes an electronic contract for the electronic business between the order-taking party and the ordering party, and provides an application for processing the electronic business regarding the electronic contract to terminals of execution group members belonging to an execution group of the order-taking party so that the execution group members process the electronic business through the terminals of the execution group