Seat slide apparatus for vehicle

A seat slide apparatus (10) for a vehicle includes an upper rail (6) retaining a seat (1) above the upper rail (6), a lower rail (5) retaining the upper rail (6) in a state where the upper rail (6) moves relative to the lower rail (5), a rolling element (20) arranged between the lower rail (5) and the upper rail (6) and a retaining member (21, 61, 71, 81) configured to retain the rolling element (20) between the lower rail (5) and the upper rail (6), the retaining member (21, 61, 71, 81) including a protruding portion (53, 63, 63A, 63B) having a top portion (P0) arranged to slidably contact with a rolling surface (S) at which the rolling element (20) rolls. The protruding portion (53, 63, 63A, 63B) includes a spreading portion (55, 55a, 55b, 65, 65a, 65b) extending from the top portion (P0)in an elongating direction, the elongating direction conforming to a path of the rolling element (20) formed on the rolling surface (S), the spreading portion (55, 55a, 55b, 65, 65a, 65b) tapering to a sharp end form with an increasing distance from the top portion (P0) in the elongating direction.