To prevent excessive tensile force from occurring and also keep a continuous-belt-like packaging bag in a folded posture at a high temperature for a predetermined time for sterilization by reciprocating a pull-out opening provided on a bottom wall of a container between an end and the other end of the container in an extension direction of the bag.

A rotary drum 14 coupled to an end of a belt-like member 12 is driven in a direction for taking up the belt-like member 12, and pulleys 9, 10 and a pull-out opening 7 are moved at a required speed against spring force of a take-up means 13. Thereafter, the rotary drum 14 is reversely rotated to take up slacks occurring on the belt-like member 12 by the spring force of the take-up means 13 for removal. The pull-out port 7 is reciprocated at a required speed to be always positioned immediately below a gradually transiting take-out part of a continuous-belt-like packaging bag 1 which has been temporarily stored in a folded posture in a container for sterilization. Thus the bag 1 can be sequentially taken out from a lower layer side with little tensile force working.