Vehicle immobilizer for preventing vehicle theft

The invention discloses a vehicle immobilizer for preventing vehicle theft, comprising a direct-current power supply, an anti-theft switch, a first triode, a second triode, a first diode, a second diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a capacitor and a relay. In use, a normally-closed switch of the relay in the vehicle immobilizer is connected with a power input end of an engine ignition system in series, the anti-theft switch is arranged in a hidden position; the vehicle immobilizer controls on and off states of the power supply through the anti-theft switch, and controls on and off states of the relay power supply through the triodes, and the resistors and the capacitor, so as to control on and off states of the normally-closed switch of the relay in order to control on and off states of the power supply of the engine ignition system. As an auxiliary device for preventing vehicle theft, the vehicle immobilizer has the advantages of being simple in structure and good in anti-theft effect, and can be arranged in a hidden manner on the basis that the original structure of the vehicle is not changed. Installation position of the anti-theft switch can be determined according to preference of the vehicle owner.