PURPOSE: To smoothly take out a container cover body from a container cover body pedestal by extending and placing the tip part of a piercing tool and a receiving hole in the work direction, and inclining the surface of an anvil of the container cover body pedestal against the work direction.

CONSTITUTION: The tip part of a piercing tool 92 is allowed to pass through a projecting piece 26 for connection of a container cover body 20 and allowed to go into a receiving hole 54. A cross-sectional area of the receiving hole 54 is made larger than that of the piercing tool 92, and a gap is provided between a side wall of the receiving hole 54 and the tip part of the piercing tool 92. In such a piercing device, at least one piece of hole is formed in the projecting piece 26 for connection of the container cover body 20 made of a metal. In this state, the tip part of the piercing tool 92 and the receiving hole are extended and placed in the work direction, and the surface 5 of an anvil of a container cover body pedestal 10 is inclined against the work direction. In such a way, a hole for increasing the connection strength of the container cover body and a gripping body can be formed in the container cover body.