Seat slide device for vehicle

A seat slide device for a vehicle comprising:

• lower rails extending in a vehicle front-rear direction and adapted to be fixed to a floor of the vehicle;
• first upper rails adapted to have a first seat of the vehicle fixed thereto and assembled to the lower rails movably in the vehicle front-rear direction;
• second upper rails positioned behind the first upper rails, adapted to have a second seat of the vehicle fixed thereto, and assembled to the lower rails movably in the vehicle front-rear direction;
• rolling members that relatively move relative to the first upper rails and the lower rails with movement of the first upper rails when a first plurality of rolling elements, which are rotatably retained by retainers between sidewall-portion inside operating surfaces formed on inside surfaces of sidewall portions extending in a vehicle vertical direction of the lower rails and sidewall-portion outside operating surfaces formed on outside surfaces of sidewall portions extending in the vehicle vertical direction of the first upper rails, roll in contact on the sidewall-portion inside operating surfaces and the sidewall-portion outside operating surfaces;
• and
• rolling element circulation units that are attached to rolling-element rolling portions of second upper rails having sidewall-portion outside operating surfaces which are configured by cutting and raising sidewall portions extending in the vehicle vertical direction of the second upper rails at sections of the second upper rails having a predetermined length in the vehicle front-rear direction, and that incorporate a second plurality of rolling elements which roll and circulate in contact with the sidewall-portion inside operating surfaces and the sidewall-portion outside operating surfaces of the rolling-element rolling portions and through surfaces opposite of the sidewall-portion outside operating surfaces of the rolling-element rolling portions.