A primary object of the present invention is to provide a hydrogen peroxide gas detection indicator which allows more certain visual recognition of color changing according to the concentration of hydrogen peroxide gas. The structure of this invention relates to an ink composition for detecting hydrogen peroxide gas containing (1) at least one of styrene acrylic resins and styrene-maleic acid resins and (2) a methine dye. According to this invention, a color-changing layer is formed using the ink composition for detecting hydrogen peroxide gas, allowing color changing according to the concentration of hydrogen peroxide gas to be visually recognized.
