1. A hydrodynamic bearing unit comprising a shaft member having a shaft portion and a flange portion, a bearing member arranged
on an outer circumference of the shaft member; and a radial bearing portion and a thrust bearing portion respectively comprising
bearing surfaces with grooves for generating hydrodynamic pressure and bearing clearances facing the bearing surfaces, and
supporting the shaft member in non-contact state, in the radial direction and the thrust direction respectively, with hydrodynamic
pressure generated in the bearing clearances when the shaft member and the bearing member relatively rotate;
wherein the squareness of the both end surfaces of the flange portion with respect to the outer circumference of the shaft
portion of the shaft member is 0.001 mm or less respectively, and the flatness of both end surfaces of the flange portion
is 0.001 mm or less respectively.
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