The object of this invention is to provide a delaminated bottle, which has a base cup fitted tightly around the bottom cylinder of the container and in which a slit is opened easily for the introduction of outside air into the interspace between the outer layer and the inner layer.The container has a male screw on the outer wall of container bottom cylinder and the base cup has a female screw, which is disposed in the upper portion of the inner surface of cylindrical cup wall and is screwed on the container bottom cylinder. The base cup has also an upright pushing section disposed in the lower portion of the inner surface of the cylindrical cup wall, and this upright pushing section pushes up on the walled bottom plate so as to open a slit in the outer layer of the pinch-off portion when the base cup is engaged with the male screw.Thus, the upright pushing section pushes up on the underside of the walled bottom plate at the time when the base cup is firmly fitted around the container bottom cylinder. The bottom seal is deformed and curved to open a slit easily and reliably so that outside air is introduced into the interspace between the outer layer and the inner layer.
