To obtain an inter-station carrier frequency synchronizing method with which carrier frequencies can be synchronized between radio stations while using a signal received from a satellite.

A radio station 2 transmits to a radio station 1 information on visible satellites from which signals can be received. On the basis of the received information on the visible satellites, the radio station 1 selects one satellite, from which a signal can be received by the radio station 1 itself, from among the visible satellites and transmits information on the selected satellite to the radio station 2. On the basis of the information from the satellite received from the radio station 1, the radio station 2 establishes synchronism with a carrier frequency of the signal received from the satellite, and the radio station 1 establishes synchronism with a carrier frequency of the signal received from the selected satellite.