A radio receiver is provided, which prevents the sensitivity of the receiver from degrading even if the receiver is applied to a communication system using a plurality of channels with unequal transmission powers. This radio receiver is comprised of an antenna for receiving a wanted RF signal; a variable-gain RF amplifier for amplifying the wanted RF signal to output an amplified, gain-controlled RF signal, a frequency converter for frequency-converting the amplified, gain-controlled RF signal to output an IF signal, a variable gain IF amplifier for amplifying the IF signal to output an amplified, gain-controlled IF signal, a despreader for despreading the amplified, gain-controlled IF signal to output a baseband signal, a Fourier transformer for conducting a Fourier transformation with respect to the baseband signal, a jamming-wave detector for detecting a jamming wave existing in a frequency range of the wanted RF signal, a demodulator for demodulating the baseband signal to output an information signal, an error-rate calculator for calculating an error rate of the information signal, and a controller for controlling gains of the variable-gain RF amplifier and the variable-gain IF amplifier.