An electronic dealing system including a host system and a plurality of terminal systems and electronically performing matching processing of information on transaction orders placed by the order side customers and information on transactions placed by hit side customers so as to establish a transaction, wherein the host system is provided with a first detecting unit for detecting the occurrence of a fault in a communication system with a terminal system and a canceling unit for canceling orders of order side customers issued from a terminal system connected to that communication system when said first detecting unit detects that a fault in the communication system has occurred.