The threshold value for a normally-off junction FET is a low value. Accordingly, in a semiconductor driver circuit using the normally-off junction FET, there have existed such problems as high-accuracy voltage control, high-speed charging into an input capacitor, and misoperations. A semiconductor driver circuit which is the most suitable for the normally-off junction FET is proposed by applying the high-accuracy gate-voltage generation scheme based on a Zener diode, a reduction in the turn-on loss based on a speed-up capacitor, the connection of an inter-gate-source capacitor, and a misoperation-preventing circuit based on the source-terminal optimum implementation scheme.