PROBLEM TO BE SOLVED: To simplify the constitution of a seedling-planting machine equipped with a planting nail. SOLUTION: The seedling-planting case 3 that actuating the seedling-planting nail 2 that is axially mounted on the seedling-planting frame is used as a split case to be jointed in the axial direction and one side of the split case is characteristically made of a metal 4 and the other is made of a plastic 5.