PURPOSE: To provide a transmission for power steering which is highly effective in power transmission, achieves a speed reduction rate required for power steering, conforms to non-reciprocal transmission structure, and also does not cause delay in rotation angle.

CONSTITUTION: A sun gear comprises the first gear 5 which is provided in a fixed shaft 4 and a second gear 7 comprising its teeth increased by one arranged coaxially side by side, and a planetary gear comprises the pinion gear 12 which is attached to a carrier 11 which can rotate around the sun gear meshed with the first gear and the second gear. The second gear is fixed to an output shaft 6 which transmit steering force to a steering system, and the shaft 9 of a motor 10 is fixed to the carrier 11 to rotate the carrier 11 by the drive force of the motor 10.