PROBLEM TO BE SOLVED: To provide a method and a device for preventing odor generation of a dehydrated cake which eliminate residual nitrite due to addition of excessive amount of nitrite and solve cost problems when nitrite is added to eliminate odor, and are applicable to prompt dehydration.SOLUTION: In the method of obtaining the dehydrated cake 11, nitrite is added to sludge slurry 1, and a polymer flocculant 7 is added and mixed to be mechanically dehydrated. The amount of the nitrite to be added is set within a range indicated by the following formula (1): 0.1<；{the amount of nitrite ion to be added (mg/L)/the amount of sulfide in sludge slurry (mg/L)}<；10 in terms of nitrite ion.【解決課題】亜硝酸塩を添加して消臭する際に、亜硝酸塩の必要以上の添加による残留やコスト的不満を解消し、即時脱水処理に適用可能な脱水ケーキの臭気発生防止方法及び装置を提供する。【解決手段】汚泥スラリー１に亜硝酸塩を添加した後、高分子凝集剤７を添加混合し、次いで機械脱水して脱水ケーキ１１を得る方法において、亜硝酸塩の添加量を亜硝酸イオン換算で下記式（１）：【数１】の範囲内とする。【選択図】図１
