Plastic and paper containers used for liquid products have some problems such as increase in amount of plastic garbage and consumption of paper resources. To solve these problems, the authors have been developed a new container for liquid of food products, which consists of a paper case made of sheet of recycled paper and a liquid packing bag made of a plastic film. In this study, the deformation of liquid packing bags, in which liquid was packaged, subjected to drop impact is investigated. Results indicated that the liquid packing bags have characteristic bulge, which vary with time, and the variation of the shape of the bags can be explained using the variation of pressure in the bags estimated from the water hammer theory.