PURPOSE: To eliminate a sense of incongruity against an abrupt change of the effect of engine braking during traveling by prohibiting switching of engine output characteristic during inertial traveling of a vehicle.

CONSTITUTION: A vehicle travels by power from an output characteristic variable engine. At this time, when an inertial traveling is detected by an inertial traveling detecting means, an output characteristic switching prohibiting means prohibits switching of engine output characteristic in answer to a signal from the inertial traveling detecting means. Thus, switching of engine output characteristic during inertial traveling is not performed, and thus a sense of incongruity against an abrupt change of the effect of engine braking during traveling can be eliminated.