A powertrain for an electric vehicle includes: a planetary gear including a first rotating element, a second rotating element, and a third rotating element, where the first rotating element is connected to a first shaft, the second rotating element is connected to a second shaft, and the third rotating element is selectively connected to a transmission housing; a first motor supplying power to the first shaft at all times; and a second motor selectively supplying power to the first shaft and the second shaft. Two rotating elements among the first, second, third rotating elements of the planetary gear are selectively connected to integrally rotate the entire planetary gear.