To provide a wheel motor in which a reduction ratio of a two-stage planetary gear speed reduction mechanism can be increased by devising its structure.

A first planetary speed reduction gear mechanism 9 comprises a drive gear 14 formed on a motor shaft 13, a first ring gear 15 formed in an inner circumference of a rotary case 8, and a free self-rotating and revolving first planetary gear 16 engaged with these both gears 14, 15. A second planetary speed reduction gear mechanism 10 is comprised of a sun gear 18 fitted through a bearing outside the motor shaft 13, engaged with a transmission gear 19 integral with a planetary gear shaft 17 rotatably supporting the first planetary gear 16 so as to transmit a driving power, a second ring gear 23 formed at an inner circumference of the rotary case 8, and a second planetary gear 24 engaged with these both gears 18, 23 which is rotatable only in its self-rotation, wherein the first ring gear 15 is made to have a larger diameter than that of the second ring gear 23.