The tsunami following the Great East Japan Earthquake that occurred on March 11, 2011 caused great damage to cultural assets and materials that were valuable to the region. The Iwate Prefectural Museum continues restoration work even now but has been faced with the trouble of unpleasant odor which was an obstacle to treatment work and storage. The present report introduces the analysis of gas emitted and chemical analysis of water used for the treatment of damaged documents. In order to identify the gas components,a conservation paper used in storage was placed in a TedlarⓇ gas sampling bag that was filled with clean air and allowed to stand at room temperature for 1 day. Then air filled with gas from the conservation paper was aerated through a sampling tube (TenaxⓇ-TA). The apparatus was introduced into a gas chromatograph/mass spectrometer (GC/MS) for qualitative analysis. Ammonium ion concentration test, sulfide ion concentration test, pH measurement, microbial cleanliness test using ATP (adenosine triphosphate)residues,and protein amount test were performed on treated water. Malodorous substances, such as acetic acid, propionic acid and butyric acid, were detected by GC/MS. In addition,many aldehydes were detected. The odorous water used for treatment had a great amount of ammonium ion, a slight amount of sulfide ion andmuch protein residues. In addition,microbial quantity increased as the treating days went on.It is presumed that the odor was created from organic matter that was decomposed by anaerobic microorganisms in the sludge. As an improvement of the treatment method, promotion of water treatment under aerobic conditions and protein removal at an early stage are to be considered. As a countermeasure for documents that already smell,repeated pressure reduction to promotegas dissipation is recommended.