A device for filling and closing disposable bags for containing banknotes includes a container for the temporary housing of one or more banknotes. The container has side walls and a bottom with an opening for the exit of the one or more banknotes from the container. A piston for pushing the 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 is wrapped around the side walls and the bottom of the container. A plate, placed below the container, is vertically movable through controlled lowering of a device, such as a spring. Sealing elements for heat sealing the filled bag are placed between the container and the plate.