To promptly detect a failure of a light source. A vehicle headlight system includes a plurality of light sources, a power supply supplying a drive voltage to the light sources, a controller individually controlling a lit/off state of each light source, and a failure detection circuit connected to the controller and detects a failure of the light sources, where, in response to a start of the vehicle, the controller executes a control operation in which all light sources are controlled from the off state to the lit state and then the light sources are controlled to the off state sequentially and individually, and where, while the control operation is executed, at least during the period of transition from the off state to the lit state of each light source, the controller acquires failure detection result and generates a warning signal when the failure is detected.