A reference voltage generator is composed of a first constant-voltage generator consisting of three p-type MOS transistors for generating a first reference voltage Vref for use in the normal operation, which is independent of an external power-supply voltage VCC and of a second constant-voltage generator consisting of two p-type MOS transistors and one n-type MOS transistor for generating a second reference voltage Vrefbi for use in a burn-in acceleration test, which is dependent on VCC. The output of each of the constant-voltage generators is feedbacked to the other constant-voltage generator as its input. Two differential amplifiers and two output drivers output, as an internal reduced voltage Vint, the higher one of Vref and Vrefbi which are outputted from the reference voltage generator. Since Vint is generated based on the two outputs Vref and Vrefbi which are outputted from the single reference voltage generator and which are related to each other, the power consumption and layout area of an internal reduced-voltage generator, which is suitable for the burn-in, can be reduced.