In a space diversity reception system, a plurality of receiving circuits, each of which is connected to respective antenna, outputs a first type signal having a level which varies in accordance with the radio frequency signal level input to the receiving circuit. An automatic gain-controlled amplifier amplifies the first type signal so as to output a second type signal having a substantially constant level. A phase control circuit detects a phase difference between the second type signal output from each of the automatic gain-controlled amplifiers and controls the phase difference in each of the first type signals to be null. A combining circuit combines the signals, whose levels are respectively following the input radio frequency signal levels, picked up from each of an inter-stage in the receiving circuits, an output of the combining circuit is the output of the space diversity system. This circuit configuration allows an employment of a less expensive automatic gain-controlled amplifier requiring less severe characteristics. Thus, a circuit for adjusting the input levels to the combining circuit can be avoided, accordingly, a multi-level quadrature amplitude modulation signal having amplitude-modulated component can be received.