Alkaline matter from concrete is an important problem in a newly built museum because it affects art objects. This paper will deal both with the mechanism of alkaline matter formation from concrete, and the alkaline matter. Its removal method and linseed- oil-soaked paper method and chemical analysis methods such as Nessler's test, the indophenol method and gas chromatography were used. The effect of both heating concrete and using adsorbents were examined as countermeasures against alkaline matter formation from concrete. It was found that the alkaline matter contains ammonia, but it is not a simple substance; when the materials of concrete such as cement and aggregate contain amino compounds, concrete emits ammonia; higher curing temperatures make seasoning time of concrete chorter; and it is possible to remove the alkaline matter from the concrete by using a suitable adsorbent.