PURPOSE: To prevent the occurrence of an engine stop by a method wherein the target number of revolutions is adjusted to a low value responding to an approximately fully closed opening by braking during running to apply engine brake the change gear ratio of which is minimum, and when a car speed is decreased to a given value due to deceleration, the target number of revolutions is increased for correction.

CONSTITUTION: A shift control valve 250 controls a servo unit for a second speed change by means of the pressurizing force of a second cam 171 of a throttle cam mechanism 150, i.e., the press force of the target number of revolutions of an engine responding to a throttle opening, and a governor pressure from a governor 8, and controls a change gear ratio. When a brake is worked during running, i.e., when an accel pedal is released from step-on, the low target number of revolutions responding to approximately full closing of a throttle opening is set, and engine brake is applied in a state that a change gear ratio is left minimum. However, when a car speed is decreased to a value lower than a given value due to deceleration, a control circuit 100 opens a second solenoid valve 285 to increase the target number of revolutions, set by the shift control valve 250, for correction, and a gear is shifted to the low side. This constitution enables prevention of the occurrence of an engine stop.