An autonomous driving system includes an electronic control unit. The electronic control unit is configured to suggest to a driver that a host vehicle overtake a preceding vehicle during autonomous driving, recognize whether the driver accepts a suggestion for the overtaking, when the electronic control unit recognizes that the driver accepts the suggestion, cause the host vehicle to overtake the preceding vehicle, and, when the electronic control unit recognizes that the driver rejects the suggestion, not cause the host vehicle to overtake the preceding vehicle, set a first prohibition duration, and, when the electronic control unit suggests to the driver that the host vehicle overtake the preceding vehicle and recognizes that the driver rejects the suggestion, extend the first prohibition duration as compared to when the electronic control unit suggests to the driver that the host vehicle overtake the preceding vehicle and recognizes that the driver accepts the suggestion.