The present invention relates to a device for sealing a packaging material (10), comprising at least one sealing installation (18) which comprises at least one coil core (24) which is surrounded by at least one coil (25), wherein the coil core (24) has at least one gap (32) through which packaging material peripheries (34, 36) to be sealed are guided, wherein at least one element (23) that conducts a magnetic flux is provided, said element (23) for influencing a region (22) of the packaging material peripheries (34, 36) to be heated being disposed so as to be adjacent to the packaging material peripheries (34, 36) to be sealed.