A power transmission apparatus of a hybrid electric vehicle may include an input shaft receiving an engine torque, an output shaft disposed at a same axis with the input shaft and outputting a shifted torque, first and second motor/generators, a first shifting section including a compound planetary gear set formed as a combination of first and second planetary gear sets, forming an adjusted torque from the engine torque received through two paths and torques of the first and second motor/generators, and outputting the adjusted torque, and a second shifting section including a third planetary gear set and outputting a shifted torque of two stages from a torque received from the first shifting section to the output shaft.