A vehicle seat sliding device includes: a lower rail fixed to a vehicle floor; an upper rail slidably engaging with the lower rail and supports a vehicle seat upward; a nut member fixed to a first rail which configures one side of the lower rail and the upper rail; a screw rod screwed into the nut member; a drive unit rotating the screw rod; and a support supporting the screw rod on a second rail which configures the other side of the lower rail and the upper rail. The support includes a holding member that is provided with an insertion hole into which the screw rod is inserted and that is fixed to the second rail, and a holding nut that is provided with a through-hole into which the screw rod is inserted and that is screwed to a screwing portion provided on the screw rod or the holding member.