A controller executes lane change control or passing control of a vehicle capable of automated driving. The controller includes at least one processor, and at least one memory which is a non-transitory tangible storage medium configured to store data and program instructions to be used by the processor. The at least one processor is, when the program instructions stored in the at least one memory is executed by the at least one processor, configured to carry out restricting the lane change control or the passing control in a case where continuation of the automated driving or smooth behavior control of the vehicle is estimated to be difficult.