To provide a pivot assembly bearing device in which an anaerobic adhesive for sticking and fixing a bearing to a shaft or a housing is unlikely to ride on end faces of an outer ring and an inner ring of a ball bearing.

A pivot assembly bearing device includes at least of a first run-off 131 and a second run-off 133. The first run-off 131 is provided to a shaft 101, has an outer diameter smaller than a surface fitted with the inner ring 103a of a ball bearing 103, and continues from a position confronted with the cylindrical surface of an inner circumference of the inner ring 103a to a range over one end face of the inner ring 103a. The second run-off 133 is provided to a housing 102, has an inner diameter larger than a surface fitted with the outer ring 104c of a ball bearing 104 and continues from a position confronted with the cylindrical surface of an outer circumference of the outer ring 104c to a range over one end face of the outer ring 104c.