PROBLEM TO BE SOLVED: To uniformly maintain the growing condition of respective seedlings in a seeded raising seedling box and dissolve useless seeding due to inappropriate growth of the seedling in the seeded raising seedling box by tiering up an unseeded raising seedling box on the raising seedling box of the uppermost part in a raising seedling box group in which a plurality of steps of the seeded raising seedling boxes are tiered up. SOLUTION: Raising seedling box receiving plates 37 project from left and right under a raising seedling box A on the position of a stopper to receive the raising seedling box A. At this time, left and right carry pinchedly holding belts 29a, 29d are let to evacuate, and the raising seedling box A is let fall on a lower tiering arm 38. The falling raising seedling box A is detected by tiered raising seedling box detecting sensors 39, and the tiering arm 38 is in order brought down up to the position detecting no raising seedling box A. Further, a seeded raising seedling box detecting sensor is arranged on a seeding device to count the seeded raising seedling box. When the raising seedling box of the uppermost part of a raising seedling box group is detected, the seeding device is once stopped so as to not to seed the raising seedling box. Thereafter the raising seedling box unseeded is tiered up on the uppermost part of the raising seedling box group.
