An automatic driving system includes an electronic control unit. The electronic control unit is configured: to create a first travel plan of a vehicle based on a position of the vehicle, an environment surrounding the vehicle, and a state of the vehicle; to calculate a first reliability of the first travel plan; to create a second travel plan of the vehicle based on one or two of the position of the vehicle, the environment surrounding the vehicle, and the state of the vehicle; to calculate a second reliability of the second travel plan; and to start the automatic driving control such that the vehicle travels based on the first travel plan when the first reliability of the first travel plan is equal to or higher than the second reliability of the second travel plan.