Four-wheel-drive vehicle and control unit for four-wheel-drive vehicle

A four-wheel-drive vehicle includes a dog clutch provided between a propeller shaft and an engine, a torque coupling provided between a rear differential and rear wheels, and an ECU that controls the dog clutch and the torque coupling. When a drive mode is switched from a two-wheel-drive mode where the transmissions of torque by the dog clutch and the torque coupling are both interrupted, to a four-wheel-drive mode, the ECU sets the amount of torque that is transmitted by the torque coupling to a first torque value (T 1 ) to increase the speed of rotation of the propeller shaft, and then sets the amount of torque that is transmitted by the torque coupling to a second torque value (T 2 ) that is lower than the first torque value (T 1 ), and engages the dog clutch when the rotations of first and second rotary members of the dog clutch are synchronized with each other.