PURPOSE: To improve the power performance without damaging the durability of a V-belt by setting a speed change pattern of a V belt type continuously variable transmission to a characteristic such that the speed is changed along the V-belt peripheral speed allowable line on the high vehicle velocity side at the full opening of a throttle.

CONSTITUTION: A speed change line of a continuously variable transmission when a throttle valve of an engine is fully opened has an engine rotating speed fixed region and a V-belt peripheral speed fixed region. In the engine rotating speed fixed region, the speed change ratio is changed in such a manner that the engine rotating speed is constant regardless of the car velocity, and when the engine rotating speed is set to a value to obtain the maximum horsepower, a satisfactory power performance can be brought out. When the car velocity is increased and enters the V-belt peripheral speed fixed region where the peripheral speed of the V-belt reaches the maximum allowable value, at the car velocity above this, the engine rotating speed is lowered along the V-belt peripheral speed allowable line, and the speed is changed in such a manner that the peripheral speed of the V-belt becomes the fixed maximum allowable value. Thus, the power performance of a vehicle can be improved without damaging the durability of the V-belt.