A liquid pourer and a method of manufacturing a packaging bag with the liquid pourer. The liquid pourer (1) for mounting on a bag body capable of increasing oxidation prevention effect on contents and accurately pouring the contents by a specified amount comprises a spool (20) moving along the axial direction of the liquid pourer (1) and an energizing member (11) having an outer peripheral surface fixed to the inner peripheral surface of the liquid pourer (1) and energizing the spool (20) to the bag body side. The liquid pourer incorporates a check valve (10) allowing only the flow of the contents from the bag body side to a ferrule part (6) side. A seat surface (19) in contact with the spool (20) energized by the energizing member (11) is formed on the energizing member (11), and the spool (20) is pressed against the seat surface (19) by the energizing member (11) to cut off the flow of the contents in the liquid pourer (1). On the other hand, when the internal pressure of the bag body or a suction force on the ferrule side reaches a specified value, the spool (20) is separated from the seat surface (19) against the energization force of the energizing member (11).