A method and apparatus of controlling a transmission power of a cognitive radio (CR) environment, the method including: sensing an incumbent user that uses a same channel as the CR environment; detecting signal quality information of the sensed incumbent user; calculating, using the detected signal quality information, a maximum transmission power value that corresponds to a maximum transmission power that may be transmitted by a CR base station in the CR environment; and controlling a communication of the CR environment to be performed within the calculated maximum transmission power value.