A normal hydraulic pressure setting means (72) calculates transmission torque on two frictional engagement elements engaged on each shift stage based on input torque and torque share and sets engagement pressure supplied to their hydraulic servos respectively. The engagement pressure is specified such that no slide takes place on the two frictional engagement elements and that one of three frictional engagement elements slides by inertial force of a vehicle as the torque share is changed even if line pressure is supplied to the hydraulic servo of another frictional engagement element being released and the three elements concurrently engage. Even if the three frictional engagement elements concurrently engage, one of them slides, so that a traveling state can be kept without using a cutoff valve, thereby reducing a size, weight and cost.