PURPOSE: To enable to easily inspect the wearing condition of lining treatment which is provided to the inside of a can body, by performing a lining treatment as same as that performed to the inside of the can body to the flat surface at the end of an inspection member which is detachably fitted to the wall surface of the can body.

CONSTITUTION: A glass lining treatment 2 is performed to the inside of a can body 1, in the wall of which a corrosion-proof electrode 4 is installed. An inspection member 6 is detachably fitted to a part of the wall of a can body, and a glass lining treatment 6a as same as that performed to the inside of a can body is performed to the flat surface at the end of a member 6 positioned inside of the can body 1. With such an arragement, the wearing condition of the glass lining treatment 2 can easily be inspected by only confirming the wearing condition of the glass lining treatment 6a, by separating the inspection member 6 from the can body 1.