A seat slide for a vehicle, including a lower rail fixed to a floor of the vehicle, an upper rail fixed to a seat of the vehicle, a lock plate disposed within an inner space between the lower and upper rails and secured to the lower rail, a latch lever with a pawl which is disposed within the inner space and pivotally supported by the upper rail, and a position sensor for detecting a position of the upper rail relative to the lower rail, the position sensor being mounted to the upper rail such that a sensing portion thereof is disposed within the inner space and opposed to the lock plate.