The frequency notifying device includes: a processor configured to store usable frequencies containing a restricted frequency being restricted in use thereof by radio equipment in a predetermined communication area and a frequency not being restricted in use thereof by the radio equipment in the communication area; and notify the radio equipment, in the communication area, of a signal for requesting the radio equipment to check whether the restricted frequency is usable or not before performing a communication using the restricted frequency when notifying the radio equipment of the usable frequency.