A device for filling and closing disposable bags for containing banknotes comprises an upper container (11) for temporarily housing banknotes (12), provided with a bottom (15) with an opening (19) for the exit of the banknotes (12) from the container (11), a piston (14) for pushing the banknotes (12) towards the opening (19) on the bottom of the container (11), a bag (13) made of flexible plastic film, intended to be filled with the banknotes temporarily housed in the container (11), a support (16) for the bag (13) containing the banknotes, vertically movable through controlled lowering means (17) and placed below the container (11), sealing bars (18) arranged between the upper container (11) and the movable support (16), intended to seal the mouth of the bag (13) upon completing the filling, and an electromagnetic stop element (26) that can be controlled to lock the movable support (16) with respect to the sealing bars (18), said electromagnetic stop element consisting of an electromagnet (27) applied to the movable support (16) and of a fixed element (28) made of ferromagnetic material, adapted to face the electromagnet (27) in operative condition.