Abstract: Provided is a power transmission device for an electric vehicle including a continuously variable transmission capable of increasing the energy efficiency and performance of the electric vehicle, further lowering the engine speed of an electric motor required for shifting the continuously variable transmission so as to accelerate the automatic gear shift timing, and further saving energy by applying a V-belt continuously variable transmission to the electric vehicle using the electric motor and providing an appropriate automatic transmission according to the driving state. The power transmission includes a housing, a driving pulley assembly disposed at the driving shaft of the electric motor, a driven pulley assembly disposed at the driven shaft, a V-belt connecting the driving pulley assembly to the driven pulley assembly, and a speed-reducing gear train disposed between the wheel axis, which is rotatably supported in the housing, and the driven shaft.