PURPOSE: To complete a lid opening operation by one action by a method wherein an openable lid has a connecting flap that is unremovably connected to a connecter formed on a lid main body, and the connecting flap is connected to the openable lid via a separable part that is cut off when the openable lid is opened.

CONSTITUTION: A connecting flap 25 formed on a opening lid 20 continues via a thin separable part 25b to a base 25a protruding downward from the part of the outer face of the openable lid 20. In addition, the connecting flap 25 is located on the right side of a hinge 31 when viewed from the hinge 31 toward a finger tab 21. The separable part 25b is of a flexible string whose thickness gradually decreases from the connecting flap 25 toward the base 25a. To open a container B, the finger tab 21 of the openable lid 20 is pushed upward to push the openable lid 20 up. Thereby, the separable part 25b of the connecting flap 25 is cut off, so that the openable lid 20 can be opened upward via the hinge 31.