To make it possible to make schedules of nurses such that nurse calls should always be answered.

A count device 22 and a clock device 21 are used to count the number of nurse calls for which a call operation part 3 of each nurse call slave machine 1 is operated for each time zone. When a determination device 24 determines that the number of such nurse calls in a time zone is equal to or greater than a predetermined number, a control device 20 registers the nursing service to be reserved for answering nurse calls in the time zone in a schedule storage device 23, so that nursing service to answer nurse calls is reserved for the time zones in which many nurse calls are made. Thus, the time zones are not scheduled tightly by other nursing services and nurses can surely answer nurse calls in the time zones.