A device for filling and closing disposable bags for containing banknotes comprises a container for the temporary housing of one or more banknotes, provided with side walls and a bottom with an opening for the exit of said one or more banknotes from the container, a pushing piston for pushing said one or more banknotes towards the bottom of the container, a bag made of flexible material intended to be filled with the banknotes temporarily housed in the container, which is wrapped around the side walls and the bottom of the container, a plate which is vertically movable through controlled lowering means and placed below the container, and sealing elements placed between the container and the plate.