A waste collecting device includes a first box including a top surface having a first opening, a bottom surface opposed to the top surface, and side surfaces connecting the top surface and the bottom surface and having a second opening, wherein the top surface, the bottom surface, and the side surfaces define a space allowing waste to be accommodated therein; a second box including a top surface, a bottom surface opposed to the top surface, and side surfaces connecting the top surface and the bottom surface and having a third opening, the third opening being in communication with the second opening; and a sending unit disposed in the first box and configured to send the waste in a direction away from the second box.