Abstract: Disclosed are an eavesdropping device detecting system and a detecting method thereof. The eavesdropping device detects the eavesdropping device based on waves generated from the eavesdropping device and displays a detecting result as a visual image, so an existence of the eavesdropping device as well as a position of the eavesdropping device can be precisely notified to the user. The eavesdropping device detecting system has a wave receiver for receiving predetermined waves, an image alarm outputting section for outputting an existence of an eavesdropping device as at least one of a message and an visual image, and a data processing section for comparing waves received in the wave receiver with waves of the eavesdropping device to judge the existence of the eavesdropping device and outputting a result thereof to the image alarm outputting section.