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 including multiple lock portions provided on the lower rail along a longitudinal direction thereof, a spindle provided on the upper rail and having a rotation axis that extends in a longitudinal direction of the upper rail, and a lock member rotating about the rotation axis and engageable with or disengageable from the lock portions. The spindle is supported by a recess portion formed in a surface of the upper rail in an inwardly extending manner.