This vehicle control system is provided with an input monitoring unit and a determination time changing unit. When a state in which first target data is not input to a second control unit continues for a first determination time or longer, the input monitoring unit determines the first target data to be in a non-input state. When a state in which second target data is not input to the second control unit continues for a second determination time or longer, the input monitoring unit determines the second target data to be in a non-input state. When the first target data is determined to be in a non-input state, the determination time changing unit shortens the second determination time.