Double container for high-viscosity liquid

A double container molded from a parison by using a split mold having at least a pair of partial molds, said parison comprising at least two layers of a rigid outer container layer and a flexible inner container layer, said two layers being partly separable from each other after molding, and external air being introduced into a space formed between said rigid outer container layer and said flexible inner container layer so that a flexible inner container being contracted while a rigid outer container being maintained in shape, the double container comprising

• a bottle body removed a bottom burr which is formed by putting the parison between at least partially bottom portions of said partial molds, and
• a covering member for isolating air-tightly an outside of the bottle body including a portion removed said bottom burr from the outside air and having a one-way valve for introducing the outside air into the space between the bottle body and the covering member.