PURPOSE: To prevent a relative rotation between a housing and an outer race and allow a shaft to be not matched with a supporting body in a ball bearing.

CONSTITUTION: A bearing assembly formed by rollingly accepting balls 48 between an inner race 40 and an outer race 44 is accepted in housings 16 and 18. Also, means 54, 56, and 58 comprising recessed and protruded parts fitted closely to each other are installed between the outer race and the housing to prevent the relative motion of the outer race and the housing.