Abstract: To restrict and further promote differential rotation between first and second output shafts, the power transmission apparatus for differentially transmitting a rotative power supplied to an input shaft to two output shafts comprises a differential gear mechanism coupled between the two output shafts; a multiplying mechanism associated with the differential gear mechanism, for detecting and multiplying a differential rotation; a motor coupled to the multiplying gear mechanism, for restricting or promoting the differential rotation by driving the multiplying gear mechanism in either direction; and a controller for controlling rotative direction and torque of the motor by adjusting supply voltage polarity and motor current magnitude. The multiplying mechanism is a strange gear mechanism or a planetary gear mechanism.