Abstract: In a bottle cap (10), a bottom cover member (40) is separated from an accommodation portion (22) while an outer peripheral wall (44) of an annular groove is pressed against a lower end surface (39) of an outer cylinder member (30) when a cap portion (26) that is threadedly mounted on the outer cylinder member (30) threadedly advances in an opening direction with respect to the outer cylinder member (30). The lower end surface (39) of the outer cylinder member (30) is inclined downward and outward. A ridge (45) is integrally formed with an upper edge of the outer peripheral wall (44) of the annular groove by the same material as that of the outer peripheral wall (44), where the ridge (45) is pressed against the lower end surface (39) of the outer cylinder member (30) while the cap portion (26) is threadedly mounted on the outer cylinder member (30).

Abstract: Provided is a powdered raw material, which is housed in a housing portion (12) of a type of a bottle cap 1 which has the housing portion (12) that houses the powdered raw material, and of which the housing portion (12) is opened by an uncapping operation, and then causes the raw material to be released into the bottle. Using a multi-functional powder property measuring instrument multi-tester, the powdered raw material is dropped onto a watch glass from a powder falling point, a dropped mass and a mass on the watch glass are measured, and a degree of dispersion which is obtained from the following formula (1) is equal to or more than 5% and equal to or lower than 40%.

Abstract: In a bottle cap (10), a bottom cover member (40) is separated from an accommodation portion (22) while an outer peripheral wall (44) of an annular groove is pressed against a lower end surface (39) of an outer cylinder member (30) when a cap portion (26) that is threadedly mounted on the outer cylinder member (30) threadedly advances in an opening direction with respect to the outer cylinder member (30). The lower end surface (39) of the outer cylinder member (30) is inclined downward and outward. A ridge (45) is integrally formed with an upper edge of the outer peripheral wall (44) of the annular groove by the same material as that of the outer peripheral wall (44), where the ridge (45) is pressed against the lower end surface (39) of the outer cylinder member (30) while the cap portion (26) is threadedly mounted on the outer cylinder member (30).