We succeeded in achieving visible-light responsiveness on a tubular TiO2 sample through the treatment of a tubular TiO2 that has a large surface area with an aqueous solution of ammonia or triethylamine at room temperature and subsequent calcination at 623 K, which produced a nitrided tubular TiO2 sample. It was found that the ease of nitridation is dependent on the surface states; washing the tubular TiO2 sample with an aqueous acidic solution is very effective and indispensable. This treatment causes the appearance of acidic sites on the tubular TiO2, which was proved by the following experiments: NH3 temperature-programmed desorption and two types of organic reactions exploiting the acid properties. The prepared samples, TiO2-delta N delta, efficiently absorb light in the visible region, and they exhibit a prominent feature for the decomposition of methylene blue in an aqueous solution at 300 K under irradiation with visible light, indicating the achievement of visible-light responsiveness on the tubular TiO2 sample. This type of tubular TiO2-delta N delta sample has merit in the sense that it has a large surface area and a characteristic high transparency for enabling photocatalytic reactions because it has a tubular structure and is composed of thin walls.