Abstract: A method of controlling silent monitoring of a group in an electronic exchange accommodating a terminal of a monitoring individual and terminals of individuals to be monitored, wherein a call between a prescribed individual to be monitored and a customer is allowed to be monitored by the monitoring individual. The individuals to be monitored are divided into groups, groups to be monitored are allocated to the monitoring individual and this information is entered into a call controller of the electronic exchange. The call controller observes, group by group, call-in-progress/call-not-in-progress status of the individuals to be monitored and allows the monitoring individual to automatically monitor, in succession, calls between customers and call-in-progress individuals to be monitored belonging to the monitoring target groups allocated to the monitoring individual.