Abstract: Method and apparatus for manufacturing spout-equipped bags in which the lateral sides of a bag are gripped by a pair of grippers, the bag is conveyed along a conveying path, and a spout is attached to the bag mouth during the conveyance. Unloading suction members adheres by suction to a bag in a horizontal orientation and takes out the bag; and then bag suction members adheres to the bag and changes the bag into a vertical orientation, the bag is then rotated through a predetermined angle, making the bag mouth horizontal. A transfer chuck grips the bag and conveys it towards grippers, and the bag is displaced a predetermined distance horizontally and supplied to the grippers. The horizontal displacement distance of the transfer chuck is set in advance such that gripping margins on the bag for the grippers are made substantially equal on the left and right of the bag.