PROBLEM TO BE SOLVED: To provide a volatilization vessel with improved operability in opening.SOLUTION: A cover cap 5 includes an opening part 61 which presses a blockage part 4 in the vessel axis O direction for removal to open a mouth part 3, and an engaging protrusion 46 which butts the shoulder part 13 of the vessel body 2 in the vessel axis O direction, accompanied by the approach movement relative to a vessel body 2 in the vessel axis O direction. The trunk part 12 of the vessel body 2 is provided with a housing part 20 for housing the engaging protrusion 46, which extends in the vessel axis O direction and opens above the shoulder part 13.
