Seat slide apparatus for vehicle

A seat slide apparatus for a vehicle (1) includes: a lower rail (11) that is fixed on a vehicle floor (1a); and an upper rail (12) that is fixed to a seat (2-4) and is movably supported on the lower rail (11) in the front-rear direction of the vehicle, wherein the lower rail (11) has a lower rail hook part (11e), wherein the upper rail (12) has an upper rail hook part (12b), wherein the upper rail hook part (12b) is to be engaged with the lower rail hook part (11e) in the upper and width directions, wherein the lower rail (11) has a curvature part (11a) that is downwards convex as viewed from the width direction of the vehicle, and wherein the lower end of the lower rail hook part (11e) at the curvature part (11 a) has a notch part (11j, 31), in which the downward extending amount is reduced compared to the other part of the lower rail hook part (11e).