SPINDLE MOTOR AND HARD DISK DRIVING DEVICE

To provide a technique capable of reducing vibrations caused by a high-order frequency of a hub.SOLUTION: In a spindle motor 1, a disk part 12 comprises: a projection part 16 in which a yoke flange part 31 is pressed; a yoke support part 18 as a contact part with which the yoke flange part 31 comes into contact, that is formed on an outer side in a radial direction than the projection part 16; and a circumferential groove 17 communicating with a gap S2 between an inner peripheral surface 13a of a hub cylindrical part 13 and an outer peripheral surface 32b of a yoke cylinder part 32, that is formed on an outer side in a radial direction than the yoke support part 18. The yoke support part 18, and a first adhesion layer L1 between the circumferential groove 17 and the yoke flange part 31 are not present in the gap S2. A second adhesion layer L2 between an inner peripheral surface 33 of the yoke cylinder part 32 and an outer peripheral surface 40a of a magnet 40 extends from an upper side of the magnet 40, and stays at a circumferential groove 35 as an adhesion layer stopping part formed on the inner peripheral surface 33 of the yoke cylinder part 32.SELECTED DRAWING: Figure 4 【課題】ハブの高次の周波数による振動を低減することができる技術を提供する。【解決手段】スピンドルモータ１において、円盤部１２は、ヨークフランジ部３１が圧入された突出部１６と、突出部１６よりも半径方向外側に形成され、ヨークフランジ部３１が当接する当接部としてのヨーク支持部１８と、ヨーク支持部１８よりも半径方向外側に形成され、ハブ円筒部１３の内周面１３ａとヨーク円筒部３２の外周面３２ｂとの間の間隙Ｓ２と連通する周溝１７とを有している。ヨーク支持部１８および周溝１７とヨークフランジ部３１との間の第１接着層Ｌ１は、間隙Ｓ２には存在しておらず、ヨーク円筒部３２の内周面３３とマグネット４０の外周面４０ａとの間の第２接着層Ｌ２は、マグネット４０の上側から延在し、ヨーク円筒部３２の内周面３３に形成された接着層止め部としての周溝３５で止まっている。【選択図】図４