A transmission unit includes a belt type continuously variable transmission (CVT) having a first pulley arranged on a first shaft with a stationary sheave, a movable sheave and a hydraulic actuator for the movable sheave. The second pulley of the CVT is mounted on a second shaft and also has a stationary sheave, a movable sheave and a hydraulic actuator. A belt is mounted around the first and second pulleys. The transmission unit further includes a synchronous transmission for connecting a first rotary member arranged on the first shaft and a second rotary member arranged on the second shaft at a constant speed ratio, an output gear for transmitting power to the wheels and a planetary gear unit. The planetary gear unit is mounted on the second shaft and includes at least first, second and third rotary elements. The first rotary element is connected to the second rotary member, the second rotary element to the second pulley, and the third rotary element to the output gear. The first shaft is connected through the CVT to the second rotary element and through the synchronous transmission to the first rotary element. The hydraulic actuators are arranged on opposite sides of the belt.