Abstract: An apparatus for limiting the maximum output of each transmission channel of a mobile communication terminal and a method thereof are provided. The method includes detecting output powers of signals, calculating differences between the detected output powers and output powers previously stored in a terminal when the detected output powers deviate from the range of a threshold value, multiplying a predetermined number by the calculated difference values to store the resultant values, and transmitting signals using the stored power values. Therefore, output power of each transmission channel is controlled so that it is possible to provide improved communication quality without interference.