PURPOSE: To enhance storage efficiency of an automatic warehouse, by storing an out-storage tray again in the same numbered rack, where it is stored before, except when a storage quantity of the tray decreases to zero and introducing a merit in both fixed and free location systems.

CONSTITUTION: An article, newly stored from the outside, is placed item by item in a predetermined tray 5, and it is carried into an automatic warehouse 40 from an in-storage line 10. The tray 5 is delivered from the automatic ware house 40 by a out-storage line, and, for instance, a necessary quantity of articles are taken out from the inside of said tray, thereafter it is stored again in the automatic warehouse 40 from a rewarehouse line 20. Cognizance parts 4a, 4b are respectively provided in a point, position before a branch point between the in-storage line 10 and the rewarehousing line 20, and a point, positioned between the branch point of the rewarehousing line 20 and a branch point of a reject lien 30, and the cognizance part reads a cognizance data 6, provided in the tray 5, to be fed to a processor 50 when the tray 5 passes through the front of the bar code readers 4a, 4b. A work station 1a, which displays a rack number condition of the automatic warehouse and the information of an in- storage instruction, is provided in the in-storage line 10.