Abstract: A ball screw device even with a small lead angle and a small number of circulation rolls, includes a rotational part, which keeps unequal division of tongue portions and legs connected to the tongue portions to a minimum and ensures the strength of the tongue portions. A recirculating part of the ball screw device includes a pair of legs, each having a tongue portion for scooping up balls in a direction approximately tangential to a spiral raceway, and a main body connecting the pair of legs. First divided faces for dividing the pair of legs along a ball recirculating path, and a second divided face for dividing the main body along the ball recirculating path are also included. The second divided face is formed by an upper divided face and a lower divided face of the ball recirculating path so that the upper divided face and the lower divided face intersect with each other when viewed from a flat surface of the nut.