To maintain an association of medical staff identification information with terminal identification information even when a portable communication terminal is taken out from a charger in place of another portable communication terminal which is connected with a charger in a nurse call system which sets a portable communication terminal to be called for each patient.

When a portable communication terminal 2 is taken out from a charger 10 before a lapse of a first predetermined time since a portable communication terminal 2 is connected with a charger 10, or when a portable communication terminal is connected with a charger 10 before a lapse of a second predetermined time since a portable communication terminal 2 is taken out from a charger 10, one portable communication terminal 2 is considered to be taken out before or after the time when another portable communication terminal 2 which a medical staff was carrying is connected with a charger 10. The medical staff identification information which is stored in association with the terminal identification information of the portable communication terminal 2 connected with the charger 10 is newly associated with the terminal identification information of the taken out portable communication terminal 2 and is stored.