A single-sheet gusset bag for photographic photosensitive materials formed of a laminated sheet comprising a metal foil layer or metallized flexible sheet layer, a water-absorptive, and heat-resistant flexible sheet layer which resists dust formation laminated on the outside of said metal foil layer or metallized flexible sheet layer, and a light-shielding polyolefin resin film layer containing at least linear low density polyethylene resin, carbon black and an antioxidant and having a thickness of more than 50 .mu.m laminated on the inside of said metal foil layer or metallized flexible sheet layer, and the bottom seal portion is turned or rolled and fixed by an adhesive or adhesive tape.