The invention relates to a seat track having a retainer arranged in a space extending in the fore-and-aft direction and the vertical direction between a lower rail and an upper rail and a lower ball and an upper ball rotatably supported on an upper portion and a lower portion of the retainer and configured to come into contact with both the lower rail and the upper rail, and is intended to provide a seat track in which vibrations in the vertical direction generated in the upper rail are reduced. There are provided a plurality of the lower balls and a plurality of the upper balls which are supported by the retainer, and a center-to-center distance between the plurality of lower balls lying next to each other is set to be different from a center-to-center distance between the plurality of upper balls lying next to each other.