PURPOSE: To improve the water resistance and falling bag strength by a method wherein a specific polyethylene film is used for an inner bag, and a bag which is made of a paper with a specific weight is used for an outer bag to constitute a double layer bag with a specific structure.

CONSTITUTION: For a packaging bag for a heavy weight article such as cement, etc., an inner bag is formed by a film made of a resin which contains a linear polyethylene, of which not more than 2g/10min, and of which flow ratio is not more than 75, and of which density is 0.910-0.965g/cm2. The tensile strength of the film in one direction (a) is not less than 600kg/cm2, the extension ratio is not more than 300%, and the tearing strength is not less than 3.5kg.cm/cm2, and the thermal shrinkage rate is not less than 60%. Also, the tensile strength of the film in a direction (b) which is rectangular to the direction (a) is not less than 400kg/cm2, and the extension ratio is not more than 900%, and the thermal shrinkage rate is not less than 30%. When the inner bag is formed, the direction (a) of the film is made the longitudinal direction of the bag. An outer bag is constituted of a paper of which weight if not less than 50g/m2, and a double layer bag is made by the inner and outer bags. In order to manufacture this double layer packaging bag, e.g. a composite material for which a film layer an a paper layer are bonded is used for bag making.