An autonomous driving system includes an information acquiring device configured to acquire driving environment information and a travelling control device configured to execute lane change control from a first lane to a second lane during autonomous driving based on the driving environment information. The travelling control device is configured to perform a continuation determining process of determining whether to continue the lane change control based on a combination of a progress level and an influence level when a subsequent vehicle in the second lane is detected based on the driving environment information and a stop request for execution of the lane change control is detected after execution of the lane change control has started. The progress level represents progress of the lane change control and the influence level represents a predicted degree of influence of continuing the lane change control on the subsequent vehicle.