A seat sliding apparatus for a vehicle includes a lower rail fixed to a vehicle floor, an upper rail fixed to a vehicle seat and supported by the lower rail so as to be movable relative thereto, and a lock mechanism. The lock mechanism includes multiple lock portions provided at the lower rail along a longitudinal direction thereof, a lock member provided at the upper rail and rotating about a rotation axis extending in a longitudinal direction of the upper rail so as to be engageable with or disengageable from the lock portions, and a bracket for supporting the lock member in a direction of the rotation axis. The seat sliding apparatus for a vehicle further includes a deflection preventing member for preventing a deflection of the bracket in the direction of the rotation axis and being integrally provided at the upper rail.