To maintain airtightness of an inner container, reduce a volume of the inner container as contents decrease and take out the viscous contents without residual by tightly inserting the flexible inner container inside a rigid outer container including a vent hole on a bottom and by adhesively fixing them with a flange.

A flexible cup-like inner container 2 having a flange is tightly inserted inside a rigid cup-like outer container having a flange and an outer flange peripheral wall 7 and including a vent hole 6 on a bottom, and they are unified by adhesive parts 4 to form a double container A. Thus an atmosphere is prevented from entering the inner container 2 from between the outer container 1 and the inner container 2 to keep airtightness. When contents 15 are taken out, the inside of the inner container 2 is at a negative pressure, and a bottom of the inner container 2 is pushed upward by difference in pressure from a bottom of the outer container 1 which is connected with the atmosphere through the vent hole 6. Thus the inner container 2 is squashed by a volume of the reduced contents 15 to have a capacity of the inner container 2 reduced.