Driving apparatus of electric vehicle and method for assembling driving apparatus of electric vehicle

A driving apparatus of an electric vehicle, comprising:

• a driving wheel;
• an electric motor case;
• an electric motor provided in the electric motor case, the electric motor having an output shaft protruding outside the electric motor case, the electric motor generating driving force of the driving wheel;
• a speed reducer case combined with the electric motor case;
• and
• a planetary gear mechanism provided in the speed reducer case, the planetary gear mechanism transferring the driving force at a reduced speed from the output shaft to the driving wheel, wherein
• the output shaft integrally includes a sun gear meshed with a planetary gear of the planetary gear mechanism,
• wherein one of the speed reducer case and the electric motor case includes a positioning section,
• wherein the positioning section is fitted into a positioning ring to determine a relative positional relationship between the electric motor case and the speed reducer case, and
• wherein a meshing length between the sun gear and the planetary gear is larger than an insertion depth of the positioning section in the positioning ring.