A method for producing a double-layered container from a parison having at least two layers of an inner layer and an outer layer for respectively forming a rigid outer layer container part and a flexible inner layer container part that are separable from each other of the double-layered container by means of a molding process of molding the double-layered container by using a split mold formed by combining at least a pair of partial parts, wherein the flexible inner layer container part can reduce it capacity while the rigid outer layer container part maintains its original profile as air is introduced between the rigid outer layer container part and the flexible inner layer container part, the double-layered container being provided with a threaded cap, characterized by comprising: step A of forming a large diameter part having a predetermined diameter at the threaded part of the mouth section of the double-layered container to be engaged with the threaded cap, at the container main body part or between them, additionally forming a small diameter part having a diameter smaller than that of the large diameter part between the large diameter part and the threaded part of the mouth section to be engaged with the threaded cap and forming a gap burr by pinching the parts of the parison corresponding to the small diameter part between at least parts of the joining faces of the pair of partial molds when the pair of partial molds are brought close to each other so as to be combined to form the split mold; step B of removing the gap burr formed in the step B; step C of screwing the cap on and applying tension to the small diameter part cleared of the gap burr in the direction for separating the threaded part of the mouth section engaged with the threaded cap and the large diameter part to produce a gap at the area of the small diameter part cleared of the gap burr; and step D of forming a shield member for airtightly shielding the gap from the atmosphere on the double-layered container, the shield member having a one way valve for allowing external air to enter the gap. step A of forming a large diameter part having a predetermined diameter at the threaded part of the mouth section of the double-layered container to be engaged with the threaded cap, at the container main body part or between them, additionally forming a small diameter part having a diameter smaller than that of the large diameter part between the large diameter part and the threaded part of the mouth section to be engaged with the threaded cap and forming a gap burr by pinching the parts of the parison corresponding to the small diameter part between at least parts of the joining faces of the pair of partial molds when the pair of partial molds are brought close to each other so as to be combined to form the split mold; step B of removing the gap burr formed in the step B; step C of screwing the cap on and applying tension to the small diameter part cleared of the gap burr in the direction for separating the threaded part of the mouth section engaged with the threaded cap and the large diameter part to produce a gap at the area of the small diameter part cleared of the gap burr; and step D of forming a shield member for airtightly shielding the gap from the atmosphere on the double-layered container, the shield member having a one way valve for allowing external air to enter the gap.