The terminal device, the operation control method thereof, and the monitored person monitoring system according to the present invention are configured to monitor the monitored person in mutually different operation modes, and to permit the operation of the outside line telephone based on the operation mode being performed And makes the outside line telephone call according to the determination result. 本発明にかかる端末装置およびその動作制御方法ならびに被監視者監視システムは、被監視者に対する監視を互いに異なる複数の動作モードで行い、前記行われている動作モードに基づいて外線電話の実施を許諾するか否かを判定し、その判定結果に応じて前記外線電話を行う。
