PURPOSE: To obtain a closed test method, a packaging method, and a commodity exterior finish method which provide a test element which has a high detection sensitivity and is simple and prompt, can test a number of specimens simultaneously and which are related to exterior finish of commodities of relatively inexpensive packagings, batteries, etc.

CONSTITUTION: A test element has at least one type of pH-indicator and the pH of the pH-indicator is set to a peculiar discoloration region which the indicator has or a surrounding of the discoloration region. For testing a packaging closed property, a gas for testing or a medium which generates a gas is placed at either inside or outside of a packaging to be inspected, a test element which changes color according to gas is placed at the opposite side, and color change of the element is measured in this state after a certain amount of time passes. For testing a closed property of exterior finish of commodities, the gas for testing or the medium which generates the gas is placed at either inside or outside of the exterior finish of the commodity to be inspected, the test element which changes color according to the gas is placed at the opposite side, and color change of the element is measured in this state after a certain amount of time passes.