A first slip travel mode is traveling or starting in a state where a first clutch is fully connected and a third clutch is fully disconnected while a second clutch is slipped. A second slip travel mode is traveling or starting in a state where the first clutch is fully connected and the second clutch is fully disconnected while the third clutch is slipped. An overheat avoidance mode is traveling or starting in a state where the first clutch is fully disconnected and the second clutch is fully connected while the third clutch is slipped. When the second clutch is in a high-temperature state under the first slip travel mode or the third clutch is in a high-temperature state under the second slip travel mode, the slip travel mode is switched into the overheat avoidance mode. This reduces a heat value of the second clutch or third clutch.