A production method of a ball screw device including: a ball screw shaft having an outer peripheral surface on which an outer-peripheral ball rolling groove is spirally formed; a ball nut having an inner peripheral surface on which an inner-peripheral ball rolling groove is spirally formed; a rolling ball that is arranged between the outer-peripheral ball rolling groove and the inner-peripheral ball rolling groove in a circulatable manner; and a retainer disposed between an outer periphery of the ball screw shaft and an inner periphery of the ball nut, and having a cylindrical portion with a retainer groove that retains the rolling ball such that radially outward movement of the rolling ball is allowed and radially inward movement of the rolling ball is restricted, characterized in that the production method comprises: a first preparation step of preparing, as a standard product, a nut subassembly into which the ball nut and the retainer are integrated with the rolling ball interposed between the ball nut and the retainer; a second preparation step of setting a plurality of dimensional groups for an outer pitch circle diameter (φDpw1) of the outer-peripheral ball rolling groove, and preparing the ball screw shaft in plurality by types as a plurality of types of ranked products, the ball screw shaft being formed such that the outer pitch circle diameter (φD1) belongs to any one of the dimensional groups and being allowed to be assembled with the standard product; a measuring step of measuring a relative displacement in a thrust direction between one ranked product among the plurality of types of the ranked products and the standard product that are assembled; a determination step of determining whether the relative displacement falls within a displacement specification; a replacing step of, if it has been determined at the determination step that the relative displacement does not fall within the displacement specification, replacing the ranked product, the relative displacement of which has been measured, with another ranked product prepared; and an assembling step of, if it has been determined at the determination step that the relative displacement falls within the displacement specification, assembling the standard product and the ranked product, the relative displacement of which has been measured, so as to form the ball screw device. a first preparation step of preparing, as a standard product, a nut subassembly into which the ball nut and the retainer are integrated with the rolling ball interposed between the ball nut and the retainer; a second preparation step of setting a plurality of dimensional groups for an outer pitch circle diameter (φDpw1) of the outer-peripheral ball rolling groove, and preparing the ball screw shaft in plurality by types as a plurality of types of ranked products, the ball screw shaft being formed such that the outer pitch circle diameter (φD1) belongs to any one of the dimensional groups and being allowed to be assembled with the standard product; a measuring step of measuring a relative displacement in a thrust direction between one ranked product among the plurality of types of the ranked products and the standard product that are assembled; a determination step of determining whether the relative displacement falls within a displacement specification; a replacing step of, if it has been determined at the determination step that the relative displacement does not fall within the displacement specification, replacing the ranked product, the relative displacement of which has been measured, with another ranked product prepared; and an assembling step of, if it has been determined at the determination step that the relative displacement falls within the displacement specification, assembling the standard product and the ranked product, the relative displacement of which has been measured, so as to form the ball screw device.