Abstract: A copy sheet stack apparatus stacks copy sheets discharged from an image-forming device and binds them be means of a staple. The apparatus comprises a first accommodating device for accommodating copy sheets discharged from the image-forming device, a staple device for binding by way of the staple the copy sheets accommodated into the first accommodating device, a second accommodating device disposed below the first accommodating device to accommodate a bundle of the copy sheets bound be means of the staple, a fall device for making the bundle of the copy sheets bound by way of the staple fall from the first accommodating device to accommodate into the second accommodating device by its own weight, and a guide device disposed between the first accommodating device and the second accommodating device to guide the bundle of the copy sheets fallen from the first accommodating device to the second accommodating device.