Abstract: The objective of the present invention is to drastically improve the running ability of a four-wheel drive vehicle by variably controlling the torque distribution ratio between the front and rear wheels. The power transfer device according to the present invention includes a transmission output shaft for receiving the power which has been varied through a transmission system; a front wheel output shaft for transferring the power to the front wheels; a rear wheel output shaft for transferring the power to the rear wheels; a front wheel clutch provided between the transmission output shaft and the front wheel output shaft, the front wheel clutch being capable of switching between an engagement state and an open state; and a rear wheel clutch provided between the transmission output shaft and the rear wheel output shaft, the rear wheel clutch being capable of switching between an engagement state and an open state.