An automatic gain control circuit able to perform high speed and correct level acquisition, able to prevent occurrence of error, and able to prevent a crash of the system. An amplification gain controller outputs a gain control signal to an automatic gain control amplifier to amplify the received signal with maximum value when receiving a burst detection trigger signal. A second gain control signal based on the detected reception signal power is calculated when receiving a first burst synchronization detection signal; and this second gain control signal is output to the automatic gain control amplifier. A received digital signal is amplified with the second gain and integrated to find the reception signal power, from which a third gain control signal is calculated and outputted to the automatic gain control amplifier to amplify the received signal with this third gain.