A power transmitting apparatus may include: an electric supplementary drive unit; a torque converting device having first, second, and third rotation elements, wherein the first rotation element is connected to the electric supplementary drive unit, the second rotation element is connected to an engine, and the third rotation element is operated as an output element; a first input shaft directly connected to the second rotation element, and a second input shaft directly connected to the third rotation element; a direct coupling device selectively connecting two rotation elements among the first, second, and third rotation elements, a first speed output unit having first and second synchronizer modules, and a second speed output unit having third and fourth synchronizer modules; and a reverse speed device having an idle gear and engaging to any one input gear on the first and second input shafts.