A notification system includes: detection means (110) for detecting an acoustic event from voice data transmitted from a communication terminal held by a target person; and notification means (120) for sending a predetermined notification when the detection means (110) has detected the acoustic event. Accordingly, it is possible to determine the state of a target person regardless of the state of this person. Further, when the difference between an acoustic pattern of the voice data transmitted from the communication terminal and acoustic patterns registered in advance is outside a predetermined range, a management server (101) does not send a notification, whereby it is possible to prevent communication traffic from being increased based on unnecessary notifications.