a four - wheel drive vehicle has a front wheel side having a front wheel set , a rear wheel side having a rear wheel set , an engine having an output shaft extending in a transverse direction of a vehicular body , a transmission having an input shaft connected to the output shaft of the engine and an output shaft connected through a transmission mechanism to the input shaft such as to extend in a transverse direction of the vehicular body , a rotating member connected to the output shaft of the transmission , a front differential gear , a first output member connected between the rotating member and one of the wheel sets for transmitting power to one of the wheel sets through the front differential gear , a second output member coaxial with the first output member , a rear wheel propeller mechanism between the second output member and the other wheel set , and operative to convert the rotation of the second output member into rotation about an axis perpendicular to the axis of rotation of the second output member for driving the other wheel set , and a hydraulic friction clutch provided coaxially with the first and second output members to selectively connect the rotating member and the second output member .