PURPOSE: To improve working efficiency of a seeding facility by seeding and step accumulation of seedling boxes while flowing plural kinds of the seedling boxes simultaneously.

CONSTITUTION: A carrier device 50 furnished with a seeding machine to seed seedling boxes and a plural number of step accumulation devices 70 to accumulate the seeded seedling boxes on a budding carriage in steps and which carries the seedling boxes from the seeding machine to the step accumulation device 70 is constituted of a primary conveyor 51 to carry the seedling boxes from the seeding machine to a specified position and a plural number of secondary conveyors 52 to carry the seedling boxes from the end edge part of the primary conveyor 51 to a plural number of the step accumulation devices 70 individually. Classification of the seedling boxes passing through the primary conveyor 51 is carried out by a sensor 55, and the seedling boxes are distributed to the suitable secondary conveyors 52 by a distribution device 56 in accordance with classification results by the sensor 55.