An automated storage/retrieval system has two pairs of multi-tier racks that are arranged in series. An elevator is disposed between the two pairs of multi-tier racks. The elevator enables a load to be delivered to and received from the two pairs of multi-tier racks. The automated storage/retrieval system having such a tandem structure not only can provide the same storage capacity as that of a conventional configuration in which two pairs of multi-tier racks are arranged in parallel, but also can be applied to a building with a limited height since the system does not need to have an extended height. Since only one elevator is needed, the number of units is less than that of a conventional system, reducing manufacturing cost and an installation space for the system.