To provide a device for manufacturing a fluid bearing, capable of independently replacing parts of a tool for manufacturing the fluid bearing, and prolonging the service life of the whole tool by replacing only the worn part, when the parts are partially worn.

A manufacturing tool 10a having plural balls 4 on its outer periphery, is inserted into a hole formed on a matter to be worked, and a groove for fluid bearing is formed on an inner peripheral surface of the matter to be worked by the relative rotation and the axial movement of the matter to be worked and the manufacturing tool 10a. The manufacturing tool 10a has a tool shaft 1a for rotatably holding the balls 4, a ball-locking member 5a demountably fitted to an outer periphery of the tool shaft 1a, and a fixing member 6a for fixing the ball locking member 5a, and the balls 4 can be replaced by demounting the fixing member 6a and the ball locking member 5a.