Disclosed is an apparatus for improving an intermodulation distortion characteristic by controlling a gain of an attenuator in a CDMA mobile terminal. The apparatus includes a converter for passing input signal components except an IF signal component, amplifying the passed input signal to a specific level, converting the amplified signal to a DC signal, comparing the DC signal with first and second thresholds, and generating a control signal for controlling an operating point of the attenuator by synthesizing the compared result signals.