PURPOSE: To prevent the deterioration of fuel consumption due to unnecessary power mode setting and reduce engine noises by changing the depth of a road load line in response to the output reduction cause of an engine or the load fluctuation cause of the engine.

CONSTITUTION: A shift line is set to the high speed side or the low speed side in response to the acceleration state based on the opening of a throttle valve 8, the vehicle speed detected by a vehicle speed sensor 7, and the detection signals from an atmospheric pressure sensor 12, an air conditioner switch 13, and an electric load switch 14, the output reduction cause or the load fluctuation cause of an engine are judged, and the depth of a road load line provided on a shift pattern stored in a shift pattern memory section 5c is changed.