To provide a transmission capable of executing fail safe operation avoiding a free running state when failure occurs according to where the failure occurs and the content of the failure.

The transmission 7 has the first failure detecting device 91 detecting the failure of the first actuator 77 or the first clutch 74 or others, the second failure detecting devicce 92 detecting the failure of the second actuator 78 or the second clutch 75 or others, and a fail safe device 93. The fail safe device 93 controls the second actuator 78 and the third actuator 79 so as to transmit torque to a drive shaft 73 via the second clutch 75 when the first failure detecting device 91 detects the failure and controls the first actuator 77 and the third actuator 79 so as to transmit the torque to the drive shaft 73 via the first clutch 74 when the second failure detecting device 92 detects the failure.