PURPOSE: To reduce in size and thickness a brushless motor and to suppress decrease in rigidity of an entire bearing and the life of the bearing.

CONSTITUTION: A bearing structure has an inner race or shaft 6, an intermediate wheel 7A, an outer wheel 7B, and a plurality of balls 8. One bearing (diameter d) is formed of the inner race or the shaft 6, the wheel 7A and the plurality of balls 8. The other bearing (diameter D) is formed of the wheel 7A, the wheel 7B and the plurality of balls 8 in such a manner that the diameter D is larger than the diameter (d).