PURPOSE: To reduce a troublesome work, and shorten a tying time by a method wherein the part of an open mouth of a bag in which a bottle under a tilted condition is packed is folded, and the folded part is tied with a tying string.

CONSTITUTION: The bottom surface part of a bottle is tilted upward or downward from the lid side of an opening part of the bottle which is located on the bottom or top, to place the bottle under a tilted condition, and a bagging of the bottle is performed. Then, the bottle packed in the bag is tilted under a condition wherein the bottle is mounted on a loading table 5, and the lid side part of the bag at the opening part of the bottle packed in the bag is folded, and the folded part 10 is tied with a string from the top. For this reason, the string which is wound on a reel 4 for the feeding of the tying string is fed by a tying string-guiding roller 4 of a projecting rod with the tying string- guiding roller, and a proper location of the folded part 10 at the opening of the bag at the lid side of the bottle packed in the bag is wound with the tying string. Then, the tying string is cut at an appropriate length to complete the tying. By this method, labor can be saved for the tying work for the opening part of a packaging bag for bottle.