CAP, CONTAINER, CONTAINER WITH CAP AND CONTAINER WITH CONTENTS STORED

To provide a cap that can maintain plug opening torque, while increasing a ratio of biomass plastics to the total mass.SOLUTION: A cap 50 comprises: a plug main body 10 made of polyolefin which is fitted to a mouth part of a container and has a discharge port which discharges contents stored in the container; an inner plug 20 made of polyolefin which has an insertion part 22 that is inserted into the discharge port, which seals the discharge port by making the insertion part 22 tightly adhere to an inner peripheral surface 14A of the discharge port; and an upper lid 30 made of poly olefin which holds the inner plug 20 and can be attached to and detached from the plug main body 10 together with the inner plug 20. A ratio Bi of biomass plastics to the total mass of the inner plug 20 is lower than a ratio of Bo biomass plastics to the total mass of the upper lid 30.SELECTED DRAWING: Figure 6 【課題】バイオマスプラスチック度を高めつつ、開栓トルクを維持することが可能なキャップを提供すること。【解決手段】容器の口部に装着され、容器に収容される収容物を吐出する吐出口を有するポリオレフィン製の栓本体１０と、吐出口に挿入される挿入部２２を有し、挿入部２２が吐出口の内周面１４Ａに密着して吐出口を封止するポリオレフィン製の内栓２０と、内栓２０を保持し、内栓２０とともに栓本体１０に対して着脱可能に構成されるポリオレフィン製の上蓋３０と、を備え、内栓２０のバイオマスプラスチック度Ｂｉが上蓋３０のバイオマスプラスチック度Ｂｏよりも低いキャップ５０を提供する。【選択図】図６