A radio communication system for mobile communications in a plurality of user terminals existing inside a moving object, comprising: a radio base station (130a, 130b) that forms a cell on a moving path of the moving object; and a radio mobile station installed in the moving object to relay communications between the plurality of user terminals and the radio base station, wherein the radio base station (130a, 130b) and the radio mobile station perform communications using a beam formed by beam forming according to one of the following: the radio mobile station forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on a geographic position of the radio base station (130a, 130b) and/or the radio mobile station; the radio base station (130a, 130b) forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on the moving path of the moving object; and at least one of the radio base station (130a, 130b) and the radio mobile station forms a beam using a weight adaptively controlled based on at least one of a traffic amount that the radio mobile station relays, a traffic configuration that the radio mobile station relays, a type of the moving object, a configuration of cars of the moving object, moving speed of the moving object, and a moving direction of the moving object. a radio base station (130a, 130b) that forms a cell on a moving path of the moving object; and a radio mobile station installed in the moving object to relay communications between the plurality of user terminals and the radio base station, wherein the radio base station (130a, 130b) and the radio mobile station perform communications using a beam formed by beam forming according to one of the following: the radio mobile station forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on a geographic position of the radio base station (130a, 130b) and/or the radio mobile station; the radio base station (130a, 130b) forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on the moving path of the moving object; and at least one of the radio base station (130a, 130b) and the radio mobile station forms a beam using a weight adaptively controlled based on at least one of a traffic amount that the radio mobile station relays, a traffic configuration that the radio mobile station relays, a type of the moving object, a configuration of cars of the moving object, moving speed of the moving object, and a moving direction of the moving object. the radio mobile station forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on a geographic position of the radio base station (130a, 130b) and/or the radio mobile station; the radio base station (130a, 130b) forms a beam using a weight selected from a plurality of weights that are candidates for selection, based on the moving path of the moving object; and at least one of the radio base station (130a, 130b) and the radio mobile station forms a beam using a weight adaptively controlled based on at least one of a traffic amount that the radio mobile station relays, a traffic configuration that the radio mobile station relays, a type of the moving object, a configuration of cars of the moving object, moving speed of the moving object, and a moving direction of the moving object.