To provide a paper pack filling nozzle having a square shape to reduce the insertion space in the conveying direction, and capable of achieving the rapid and consistent filling with a check and a displacer being exclusively designed.

The paper pack filling nozzle has the square shape while a check valve 1, a displacer 4, and a screen mesh 3 are arranged therein. Further, the check valve capable of executing the suction-back is used.