PROBLEM TO BE SOLVED: To provide a volatilization device that can suppress degradation of a lid due to an agent.SOLUTION: A volatilization device 10 has: an annularly continuous peripheral wall 22 fitted into an edge of an opening of a container 1 that stores a volatile agent； a ceiling wall 24 that has a volatilization hole 21, continues to one end of the peripheral wall in axial direction, and faces the opening； and a slit 26 provided between the peripheral wall and ceiling wall.SELECTED DRAWING: Figure 1【課題】薬剤による蓋の劣化を抑制できる揮散装置を提供する。【解決手段】本発明の揮散装置１０は、揮発性を有する薬剤を収容した容器１の開口部の縁に嵌合する環状に連続した周壁２２と、揮散孔２１を有して周壁の軸方向の一端に連続し、開口部に対向した天壁２４と、周壁と天壁の間に設けたスリット２６と、を有する。【選択図】図１
