In an automatic gain control amplifier ( AGCa ), an RF automatic gain controller (2) controls the gain of a radio frequency signal ( Srf ). A frequency converter (3, 4) frequency-converts the radio frequency signal ( Srfa ) into an intermediate frequency signal ( Sifa ). An IF automatic gain controller (5) controls the gain of the intermediate frequency ( Sifa ). A level detector ( LDa ) detects a signal level of the gain-controlled intermediate frequency signal ( Sifa ), and generates a level signal ( SLa ). An automatic gain control signal generator (SGa, SGb) separately controls, based the level signal ( SLa, SLb ), the RF automatic gain controller (2) and the IF automatic gain controller (5).