A dynamic semiconductor memory device of the random access type having an initialization circuit which controls the switch-on operation of the semiconductor memory device and of its circuit components. The initialization circuit supplies a supply voltage stable signal once the supply voltage has been stabilized after the switching-on of the semiconductor memory device. The initialization circuit has an advance detector circuit, which detects a predetermined level state of an externally applied clock control signal chronologically before the supply voltage stable signal is generated and, as a reaction to this, supplies a first enable signal for unlatching the control circuit provided for the proper operation of the semiconductor memory device.