Disclosed is an inexpensive fluid dynamic bearing device exhibiting high
bearing performance and long life. A fluid dynamic bearing device (1) is
mainly composed of a shaft member (2), and a bearing member (7) equipped
with a cylindrical radial bearing surface (A) opposed to an outer
peripheral surface (2a) of the shaft member (2). The bearing member (7)
is formed by injection molding with an electroformed portion (10)
inserted, and the radial bearing surface (A) is formed on the
electroformed portion (10). Further, a thrust bearing surface (B) is
formed on an upper end surface (7b) of the bearing member (7), and the
shaft member (2) is supported in a thrust direction by a dynamic pressure
action of a lubricating fluid generated in a thrust bearing gap opposed
to the thrust bearing surface (B).