A mobile radio communication system which does not need an omnidirectional channel for both a base station and a mobile station to track each other and uses only a narrow beam channel and can reduce a tracking time than before for an adjacent base station and a mobile station to search each other while a visiting area base station and the mobile station are communicating in the overlapped area. The base station and the mobile station comprise a unit for transmitting and receiving in forward or reverse channel, in different frequency, in different tracking channel using a narrow beam. Both the mobile station and the visiting area base station search the location each other, and after searched, they assign the frequency and the beam used in the tracking channel. At the same time, by comprising a searching slot in an information channel to search an adjacent base station while communicating with the visiting area base station, a tracking of other adjacent base station can be performed.