A surrounding information acquisition section and a recognition unit (a surrounding detection unit) detect a first position (a change position) at which the type of a lane mark is switched. A lane change determination unit outputs a determination result whether lane change is available or unavailable on the basis of the type of the lane mark ahead of the first position to a notification mechanism (a notification unit) at a time point at which a vehicle has reached a predetermined range including the first position. The notification mechanism makes notification of the determination result.