A powertrain apparatus for an electric vehicle may include a motor connected to an input shaft, a planetary gear train, which is disposed to be coaxial with the motor and which includes a first rotation element, a second rotation element and a third rotation element, at least one of which is configured to receive power from the input shaft, a differential gear disposed to be coaxial with the motor and the planetary gear train, a first gear set connected to one rotation element of the planetary gear train, and a second gear set configured to receive power from the first gear set and transmit the power to the differential gear.