PROBLEM TO BE SOLVED: To provide a chemical volatilizer capable of appropriately switching between opening and closing of a vent hole formed in a housing. A drug volatilizer includes a first case that holds a container from which a drug exudes so as to cover the container from the outside, and a second case that holds the container so as to cover the first case from the outside. A ventilation hole is formed in the first case. The second case can be switched between a closed position for closing the vent and an open position for opening the vent by rotating around the rotation axis with respect to the first case. The first case has a front side member and a back side member that are removable in the front and rear. A first restricting element is provided on the front member. The rear surface member is provided with a second restricting element that is caught by the first restricting element so as to restrict rotation of the front surface member around the rotation axis relative to the rear surface member. [Selection diagram] Fig. 7【課題】筐体に形成される通気口の開閉を適切に切り替えることができる薬剤揮散器を提供する。【解決手段】薬剤揮散器は、薬剤が滲出する容器を外側から覆うように保持する第１ケースと、第１ケースを外側から覆うように保持する第２ケースとを備える。第１ケースには、通気口が形成される。第２ケースは、回転軸周りを第１ケースに対し回転することにより、通気口を閉じる閉位置と、通気口を開く開位置との間を切り替えられる。第１ケースは、前後に取り外し可能な正面側部材と背面側部材とを有する。正面側部材には、第１規制要素が設けられる。背面側部材には、正面側部材が回転軸周りに背面側部材に対し相対的に回転するのを規制するように、第１規制要素に引っ掛かる第２規制要素が設けられる。【選択図】図７
