An inverter control device, comprising: a main power supply ; a sub power supply which converts an electric power distributed from said main power supply ; a controller which operates with an electric power for control supplied from said sub power supply ; a transistor which makes an input signal of said controller turn ON/OFF, by having a current between an emitter and a collector made to turn ON/OFF; and a power-supply monitoring circuit of which input terminal is connected to said main power supply via at least a resistor (rD) so as to monitor a voltage of said main power supply , characterized in that an emitter terminal of said transistor is grounded, a base terminal of said transistor is connected to an output terminal of said power-supply monitoring circuit via a resistor (rB), and said current between said emitter and said collector of said transistor is made to turn ON/OFF according to an output signal of said power-supply monitoring circuit ; wherein said output terminal of said power-supply monitoring circuit is connected to said main power supply via at least a resistance (rA), that said input terminal of said power-supply monitoring circuit is grounded via an earth resistance (rE), and that said base terminal of said transistor is grounded via a resistance (rC). a main power supply ; a sub power supply which converts an electric power distributed from said main power supply ; a controller which operates with an electric power for control supplied from said sub power supply ; a transistor which makes an input signal of said controller turn ON/OFF, by having a current between an emitter and a collector made to turn ON/OFF; and a power-supply monitoring circuit of which input terminal is connected to said main power supply via at least a resistor (rD) so as to monitor a voltage of said main power supply , characterized in that an emitter terminal of said transistor is grounded, a base terminal of said transistor is connected to an output terminal of said power-supply monitoring circuit via a resistor (rB), and said current between said emitter and said collector of said transistor is made to turn ON/OFF according to an output signal of said power-supply monitoring circuit ; wherein said output terminal of said power-supply monitoring circuit is connected to said main power supply via at least a resistance (rA), that said input terminal of said power-supply monitoring circuit is grounded via an earth resistance (rE), and that said base terminal of said transistor is grounded via a resistance (rC). an emitter terminal of said transistor is grounded, a base terminal of said transistor is connected to an output terminal of said power-supply monitoring circuit via a resistor (rB), and said current between said emitter and said collector of said transistor is made to turn ON/OFF according to an output signal of said power-supply monitoring circuit ; wherein said output terminal of said power-supply monitoring circuit is connected to said main power supply via at least a resistance (rA), that said input terminal of said power-supply monitoring circuit is grounded via an earth resistance (rE), and that said base terminal of said transistor is grounded via a resistance (rC). <EOS>