A device and method for allocating channels from a base station to a mobile station run with a CDMA Cellular System that includes a first step for measuring the strength of a signal received, a second step for calculating the margin allowed for signal strength by subtracting the size of a signal received, measured in the first step from the total interference allowed, a third step for evaluating whether the margin calculated in the previous step has not been exceeded upon receiving a new radio channel request from a mobile station, and a fourth step for allocating a radio channel to a requesting mobile station when the evaluation result shows that the required power is less than the margin. By utilizing the present invention to allocate a radio channel in accordance with the strength of a signal received by the receiving unit of the Base Station, the utilization of the radio resources of a CDMA System can be maximized and they can be easily used, and as a result, economic CDMA system services can be ensured.