An aseptic filling and packaging apparatus, comprising: a supplying device for gaseous hydrogen peroxide; a sterilization chamber through which a film sheet passes, and to which gaseous hydrogen peroxide is supplied from the supplying device; a ventilation chamber through which the film sheet passes, the ventilation chamber being located downstream of the sterilization chamber; a ventilator adapted to ventilate the ventilation chamber; a filling and packaging chamber that is located downstream of the ventilation chamber, wherein the filling and packaging chamber comprises a film forming device adapted to form the film sheet into a plastic film packaging bag (1, 101, 201) in a shape of a bag, and a filling device adapted to fill fills the plastic film packaging bag (1, 101, 201) with a material, wherein the filling and packaging chamber is ventilated by the ventilator; a first line that connects the supplying device to the sterilization chamber, characterized in that the apparatus further comprises; an antechamber that is located upstream of and adjacent to the sterilization chamber, wherein the film sheet passes through the antechamber and the antechamber is ventilated by the ventilator; a second line that branches from the first line; and a third line adapted to introduce outside air to the ventilation chamber and to the filling and packaging chamber, wherein the second line merges with the third line, further comprising a valve that is provided on the second line, and a controller that controls the valve, wherein the controller is adapted to control opening and closing of the valve such that a start-up sterilization process and a production sterilization process are switched from one to the other, wherein, in the start-up sterilization process, gaseous hydrogen peroxide is supplied to the ventilation chamber and to the filling and packaging chamber via the second line and the third line, and in the production sterilization process, outside air is supplied to the ventilation chamber and to the filling and packaging chamber via the third line. a supplying device for gaseous hydrogen peroxide; a sterilization chamber through which a film sheet passes, and to which gaseous hydrogen peroxide is supplied from the supplying device; a ventilation chamber through which the film sheet passes, the ventilation chamber being located downstream of the sterilization chamber; a ventilator adapted to ventilate the ventilation chamber; a filling and packaging chamber that is located downstream of the ventilation chamber, wherein the filling and packaging chamber comprises a film forming device adapted to form the film sheet into a plastic film packaging bag (1, 101, 201) in a shape of a bag, and a filling device adapted to fill fills the plastic film packaging bag (1, 101, 201) with a material, wherein the filling and packaging chamber is ventilated by the ventilator; a first line that connects the supplying device to the sterilization chamber, characterized in that the apparatus further comprises; an antechamber that is located upstream of and adjacent to the sterilization chamber, wherein the film sheet passes through the antechamber and the antechamber is ventilated by the ventilator; a second line that branches from the first line; and a third line adapted to introduce outside air to the ventilation chamber and to the filling and packaging chamber, wherein the second line merges with the third line, further comprising a valve that is provided on the second line, and a controller that controls the valve, wherein the controller is adapted to control opening and closing of the valve such that a start-up sterilization process and a production sterilization process are switched from one to the other, wherein, in the start-up sterilization process, gaseous hydrogen peroxide is supplied to the ventilation chamber and to the filling and packaging chamber via the second line and the third line, and in the production sterilization process, outside air is supplied to the ventilation chamber and to the filling and packaging chamber via the third line.