To provide an automatic warehouse capable of preventing two carrying-in/shipping devices from carrying out transfer operation simultaneously to the same shelf of a rack from front/back sides of the rack.

The automatic warehouse comprises a rack 2 having a plurality of shelves 1, a first carrying-in/shipping device 3A for transferring articles from the front side of the rack 2, and a second carrying-in/shipping device 3B for transferring articles W from the back side of the rack 2. At least one carrying-in/shipping device is equipped with a detection means 17 for detecting the other carrying-in/shipping device at the opposite position across the rack 2. The detection means 17 is, for example, a light receiving means for receiving light from a light projecting means 18 installed in the other carrying-in/shipping device on the opposite side.