To provide an unstacking device, a stacking device, and an unstacking/stacking device not requiring any plurality of actuators nor an air supply source, and as its result, assuring a simple control.

The unstacking device is composed of engaging members 51 installed on both sides of a transporting means 12 in such a way as to rise and fall and also revolve and capable of being located in the advanced position to hold an storage box W and the retreated position lying out of the interfering region with the storage box, an elevating/sinking means 20 to elevate and sink the engaging member 51 between the holding position to hold the storage box W and the release position to release it, and a swinging means 50 to revolve the engaging member. The elevating/sinking means 20 is equipped with a motor 23, a power diverging means 24 to diverge a rotational power, and a power converting means 30 to convert the rotational power into rising and falling motions of an elevating/sinking plate 41, while the swinging means 50 is equipped with a rack 54 fitted with a flat gear 53 and a meshing roller 55, a first cam 62 to move the rack 54 toward the center of the transporting means through the roller 55, and a second cam 63 to move to the opposite side.