PROBLEM TO BE SOLVED: To provide an apparatus for suppressing mold odor in an internal occupation space which can be operatively connected to a mounting part for detachably attaching to a vent hole of an automobile.SOLUTION: There is provided a device comprising a reservoir containing a volatile composition in fluid communication with a substrate, more preferably a microporous membrane, wherein the volatile composition comprises at least 0.2 wt% of a C5 to C8 non-branched, unsubstituted linear alkenal and at least 0.2 wt% of a C9 to C14 non-branched, unsubstituted linear alkenal based on the volatile composition.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】自動車の通気口に着脱可能に取り付けるための装着部分に動作可能に接続可能な内部占有空間内のカビ臭を抑制するための装置の提供。【解決手段】より好ましくは微多孔質膜である基材と流体連通した揮発性組成物を収容するリザーバを有し、揮発性組成物は揮発性組成物の少なくとも0.2重量%のC5~C8の非分枝非置換の直鎖状アルケナールと、少なくとも0.2重量%のC9~C14の非分枝非置換の直鎖状アルケナールとを含有する装置。【選択図】なし