an alerting device allowing easy estimation of possible interference and useful suggestions to eliminate deteriorated communication quality due to interference is disclosed . a signal including a band used by a target radio communication system is selected from a received signal based on a prescribed system specification of the radio communication system . a detected signal level of the selected signal is detected and compared with the prescribed interference level . when the detected signal level is greater than the prescribed interference level , it is determined that interference occurs . further , an interference source is estimated by analyzing the selected signal with respect to time and frequency components .