100 b and the forward voltage of the current regenerating diode 261 as compared with the ease in which the same clamping voltage is generated between the drain and source of the downstream side drive fet 220 1 and therefore heat generation of the zener diode 262 is suppressed correspondingly further the desired clamping voltage 320 can be realized by properly selecting the zener diode 262 fig3 shows a circuit configuration of embodiment 2 of the internal combustion engine controller according to the present invention and the typical operation waveform of each of the parts thereof is shown in fig1 in the embodiment 2 a voltage regulating section is configured by a mosfet 263 zener diode 264 and a resistor 265 in the circuit of embodiment 1 the mosfet 2 63 is interposed in series with the current regenerating diode 261 in such a manner that a drain thereof faces the downstream side of the injector 3 1 and a source thereof faces the boost voltage side the zener diode 264 is connected in such a manner that a cathode of the zener diode 264 faces the drain of the mosfet 263 and an anode faces a gate and the resistor 265 is connected to between the gate and the source of the mosfet 263 since in the circuit configuration of embodiment 2 the voltage between the drain and the source of the mosfet 263 is determined by the zener diode 264 the clamping voltage 320 of the injector 3 1 has the total value of the boost voltage 100 a the forward voltage of the regenerating diode 261 and a zener voltage of the zener diode 264 and can be set to a voltage higher than the boost voltage 100 a the mosfet 263 of embodiment 2 is.