A level converter circuit is provided for converting an input signal of a digital signal having a first signal level into an output signal having a second signal level higher than the first signal level. An amplifier circuit amplifies the input signal and outputs an amplified output signal, and a current generator circuit generates a control current corresponding to an operating current flowing through the amplifier circuit upon change of the signal level of the input signal. A current detector circuit detects the generated control current, and controls the operating current of the amplifier circuit to correspond to the detected control current. The current generator circuit includes series-connected first and second nMOS transistors as inserted between the current detector circuit and the ground. The first nMOS transistor operates responsive to the input signal, and the second nMOS transistor operates responsive to an inverted signal of the input signal.