In a linked notification system configured by communication-connecting at least one external device to a portable notification device, on receipt of a state signal indicating a state of the external device from the external device, the portable notification device refers to the notification control information in which a notification destination is associated with a notification condition defined by using a state of the external device, and determines whether the notification condition is satisfied or not on the basis of the state signal. When it is determined that the notification condition is satisfied, the portable notification device notifies the notification destination associated with the notification condition.