The invention relates to a fault injection device. The fault injection device comprises an operation panel used for setting a type of a fault signal needing injection, a signal collection module used for filtering and shaping a signal from a vehicle sensor to generate an original signal and inputting the original signal to an MCU, an MCU for processing the signal outputted from the signal collection module to generate a fault injection signal meeting the type of the fault signal needing injection as an output signal according to the type of the fault signal needing injection received by the operation panel in a situation that there is a fault injection mode or employing the original signal from the signal collection module as an output signal directly in a situation that there is not a fault injection mode, and a signal output module for receiving the output signal from the MCU and outputting a square wave signal or a simulation signal to an electric control module to be detected. By utilization of the fault injection device, fault injection with various types can be achieved.