The present invention provides a double container capable of suppressing the deterioration of the gas barrier property under high humidity environment. According to the present invention, provided is a double container comprising a container body, wherein the container body has an outer shell and the inner bag, the container body is configured such that the inner bag contracts as content is reduced, and the inner bag comprises an inner layer, a gas barrier layer, and an outer layer, in order from an inside of the container body.

A preform is made of a thermoplastic material and is used to manufacture blow-molded containers. The preform has a tube-like central area, a closed bottom and a mouth section. The mouth section lies opposite the bottom in the direction of a longitudinal axis and defines an interior space. The wall thickness in the area of the bottom is at least partially smaller than in the central area. In the region of an inner or outer surface, the bottom has at least one protrusion and optionally a web. The axial web extends from a center of the bottom in the direction of the central area. The vertical web can connect at least two axial webs with each other or be designed alone. The protrusion and the optional webs are formed by a melting chamber and flow channels following the material feed via the sprue.