Traction motors are required to be small and lightweight to settle in a limited space between wheels, and to have high power for high speed running. Furthermore, they must have a long life and high efficiency at low noise levels without requiring much maintenance work. New techniques to reduce weight and increase output of traction motor are reviewed, with respect to insulation materials, structural materials, magnetic materials, cooling system, replacement of dc traction motor with a new induction traction motor, etc. Direct drive traction motors which eliminate conventional flexible couplings and reduction gears are introduced Finally, future trends in the development of traction motor are examined.