Abstract: An automatic conveyance system comprises a buffer storage for storing a plurality of unit racks containing units; a plurality of test cells for testing the units contained in the unit racks; and a plurality of test cell controllers, each being provided in one of the test cells and each accepting an operator's requirement to take out a unit rack from the buffer storage, to store a unit rack into the buffer storage, or to convey a unit rack from one of the test cells to another one of the test cells. The system is provided with a plurality of automatic guided vehicles for conveying unit racks. A computer is connected to the test cell controllers by a single bus and has information on the unit racks stored in the buffer storage.