The present invention relates to an apparatus capable of flexibly regulating coverage of a repeater in a long term evolution system (hereinafter referred to as an LTE system). The present invention provides an apparatus for regulating transmission power of a repeater in an LTE (LONG TERM EVOLUTION) system, the apparatus including a sink signal detector that detects a sink signal of a reception signal received through an IF/RF receiver of the repeater, a sink signal power measurer that measures a size of power of the sink signal detected through the sink signal detector, and an amplification controller that calculates a gain of an amplifier of the repeater for maintaining coverage of the repeater based on the size of the power of the sink signal measured through the sink signal power measurer, and controls the amplifier of the repeater according to the calculated gain. In the present invention, in a wired or wireless repeater, it is possible to efficiently regulate the coverage of the repeater and to implement the apparatus with low complexity in the LTE system. Further, the present invention is flexibly applicable to an LTE system supporting a scalable bandwidth and it is possible to effectively regulate the coverage of multiple LTE signals using signal amplification for multiple LTE signals.