When conditions have not been satisfied from a timing at which a first position of the interflow zone was set to a timing at which the subject vehicle reaches the first position, the first position is set as a start position where a notification for urging a handover of a central player of the subject vehicle is performed. When the condition for automatic interflow is satisfied for the first time at the timing at which the subject vehicle reaches the first position, a second position between the first position and a distal end of the interflow zone is set as the start position.