Ball screw device

A ball screw device comprising:

• a nut that has an inner peripheral raceway surface on an inner peripheral surface;
• a screw shaft that is inserted into the nut and has an outer peripheral raceway surface on an outer peripheral surface;
• a plurality of balls disposed on a raceway between the outer peripheral raceway surface and the inner peripheral raceway surface;
• and
• at least one deflector that circulates the plurality of balls, wherein
• the outer peripheral surface of the screw shaft is provided with at least one recess that is recessed radially inward and accommodates the deflector,
• the recess has an inner peripheral surface provided with two screw shaft openings in the outer peripheral raceway surface, the two screw shaft openings opened toward the deflector,
• the deflector includes:
• a pair of deflector openings opened in an outer peripheral surface of the deflector and connected to the two screw shaft openings,
• a circulation groove surface that is connected to each of the pair of deflector openings and has an internal space forming a circulation pathway, and
• a pair of tongues disposed radially outside the circulation groove surface and protruding toward the pair of deflector openings, and
• the pair of tongues each has a tip disposed radially outside a virtual spiral connecting centers of the plurality of balls rolling on the raceway.