A switching valve is provided which operates hydraulic friction engaging elements in a combination to establish a fifth speed "5th" when in a first position, and in a combination to establish a third speed "3rd" when in a second position, when a first electromagnetic valve to a fifth electromagnetic valve fail so as to stop operating. As a result, in the event of failure while driving, the fifth speed "5th" is first established to enable the vehicle to continue running. Then, when the position of a manual valve is changed by an operation by the driver when the vehicle is stopped or the like, the switching valve shifts a transmission into the third speed "3rd", which has a larger gear ratio than the fifth speed "5th", to ensure the driving force required to take off again.