To easily and rapidly assemble an electric wheel incorporating an electric motor and a wedge roller type transmission in the wheel.

First, a holding ring 33 is inserted in the wheel 1 and fixed by a bolt 34 through a washer. Next, an output ring (an outer ring) 32 is inserted in the holding ring 33 and fixed by a snap ring 35. This constitutes a wheel assembly A. Next, the electric motor 5 is assembled, a wedge roller type transmission 6 excluding the output ring (an outer ring) 32 is assembled, these two are coupled together to constitute a friction roller motor assembly B. The friction roller motor assembly B assembled in the manner described above is inserted in the wheel assembly A assembled in the manner described above to assemble the electric wheel and fixed by a snap ring 50.