A bag-filling packaging machine in which supplied bags 1 are gripped by pairs of grippers 2 disposed on the periphery of an intermittently turning round table 3, and the bags, at stopping positions, are successively subjected to prescribed packaging operations with the gas inside the bags being replaced during that process, wherein a pair of guide members 15 and 16 for keeping the bag mouth opened is provided on the table 3 in correspondence with each of the gripper pair, and guide members 15 and 16 are connected to an inactive gas supply source and have gas blow-out ports at the tip ends that are inserted inside the bags, thus allowing the guide members 15 and 16 to not only keep the bag mouth opened but also function as gas blow-in nozzles.