A seat sliding structure for a vehicle includes: a pair of left and right slide rails that include upper rails, which are attached to a lower portion of a vehicle seat, and lower rails, which support the upper rails such that the upper rails can slide in a vehicle longitudinal direction; rail guiding members that are fixed to a floor panel, and that support the lower rails such that the lower rails can slide in the vehicle longitudinal direction between a driving position at a vehicle front side and a relaxation position at a vehicle rear side; and a locking mechanism that locks movement of the slide rails at the relaxation position, and that releases a locked state when a frontal collision of the vehicle is detected or predicted.