To supply a pivot assembly for hard disk drive use that can reliably fix a seal member and solve the problem of out gas, thus reducing the expense and time incidental to the pre-load of a ball bearing. Ball bearings have been joined to both ends of a shaft, and on the outer circumference of these ball bearings, the spacer part is joined to a sleeve disposed between both ball bearings, and a seal member that covers the outer end of the ball bearing has been fixed to the outer circumference of the shaft by laser welding. Because the seal member is fixed by laser welding, the seal member can be reliably fixed and the problem of out gas from the seal member can be solved.