A slide rail device for a vehicle includes a lower rail; an upper rail supported on the lower rail to be slidably movable relative thereto; a lock mechanism between the upper and lower rails; a lock-operation lever inserted into the upper rail; a rotational supporter supporting the lock-operation lever to be rotatable between locked and unlocked positions; a handle; a biasing spring having an engaging portion which engages with the lock-engaging portion so that the engaging portion is immovable relative to the lock-engaging portion wherein the biasing spring supports the rear-end portion of the handle; and a spring support portion, provided on the upper rail, which is positioned immediately below the biasing spring and prevents the biasing spring from falling downward from an underside opening of the lock-operation lever when the rotational supporter supports the lock-operation lever.