Abstract: The present invention relates to a repeater for amplifying signals transmitted and received between a communications terminal such as cellular phone and a base station and, more particularly, to a repeater for mobile communications system, which amplifies the signal received from the communications terminal accommodatively to intensity of the signal, or correlatively with the existence of the input signal, and transmits the amplified signal to the base station. The repeater of the invention establishes a line coupler 7 on a transmission line for a first amplifier 5 amplifying the frequency signal received from the terminal and divides the frequency signal input to the first amplifier 5. A gain control signal generator 8 generates a gain control signal corresponding proportionally to a level of the frequency signal divided by the line coupler 7 and applies the gain control signal to the first amplifier 5.