An internal-circulation-type ball screw having simple construction and high productivity is provided. A ball nut has one or more through holes and one or more constrictions, which are formed around its outer peripheral surface so as to span the openings of respective through holes. One or more deflectors are put in respective through holes and fixed by fitting corresponding deflector-locking springs onto the constrictions. Each deflector-locking spring is a thin plate spring having a substantially C-shaped cross section with a concave portion in the middle. When the deflector-locking spring is fitted onto the constriction, the concave portion thereof presses the deflector in the through hole toward the threaded shaft. Thus, the deflector is fixed to the ball nut.
