SPINDLE MOTOR

PURPOSE: To provide a thin spindle motor having a high rotation accuracy. CONSTITUTION: An upper collar portion 16b and a lower collar portion 16d are provided above and below a shaft portion 16a of a rotation shaft body 16. A sleeve portion 12a of a fixed bearing body 12 is fitted through a lubricating agent over the shaft portion 16a thereby constituting a radial dynamic pressure bearing portion 18. An upper ring-shaped portion and a lower ring- shaped portion of the fixed bearing body 12 are placed oppositely through the lubricating agent relative to the lower side surface and the upper side surface of the upper collar portion 16b and the lower collar portion 16d, and an upper axial dynamic pressure bearing portion 20 and a lower axial dynamic pressure bearing portion 22 are constituted. An inner peripheral portion of a rotor frame 36 fitted over a projected portion 16c of a rotating shaft body 16 is sandwiched tightly between an upper surface of the upper collar portion 16b and a cap member 38 and fixed.