A basic structure of a reference voltage generation circuit is formed by a buffer amplifier (21) and a resistive element (22) without using a band gap regulator. Thus, an influence of a noise of the band gap regulator as in the conventional art is eliminated. There are provided comparators (23) and (24) for comparing an input voltage of the buffer amplifier (21) with an output voltage of a band gap regulator (10), and a control circuit (25) for variably controlling a resistance value of the resistive element (22) in response to comparison signals. Consequently, even if an output voltage (Vout) of the buffer amplifier (21) temporarily fluctuates with a change in a source voltage (VDD), it returns into a desirable voltage range and converges through a variable control of the resistance value.