An upper-limit vehicle speed should be prevented from being set to speed different from an intention of a driver. When it is detected that a speed limit is changed, an upper-limit vehicle speed setting ECU temporarily switches a control mode from a normal mode to an inquiry mode. An ASL operation unit serves a function for a change operation of upper-limit vehicle speed in the normal mode, and serves a function for a reply operation about whether the speed limit is accepted in the inquiry mode. When the ASL operation unit is operated in the normal mode, the upper-limit vehicle speed setting ECU does not switch the control mode to the inquiry mode, even if a change of a speed limit is detected, until a certain period of time (a certain period during which a mode switching prohibition period is set) has passed since the operation.