A slide device for vehicle seat in which rollers are arranged at three positions on a lower rail including front and rear portions thereof. Among the rollers, the rollers located at the front and rear portions of the upper rail are pivotally supported by roller shafts and that are prohibited from moving on the upper rail, while the rollers located at the position other than the front and rear portions of the upper rail are pivotally supported by a roller shaft that is allowed to move downward on the upper rail.