[Problem] To provide a sterilization instrument such that the occurrence of a "liquid pool" is suppressed and heated liquid can be prevented from being scattered therearound. [Solution] This sterilization instrument 60 is provided with: a medium supply part 61 for supplying a heated sterilization medium into an object 100 to be sterilized； and a support part 70 for supporting an opening 110 of the object to be sterilized, the opening being where the sterilization medium is discharged from the object. The sterilization instrument 60 is configured so that the sterilization medium discharged through the opening of the object is discharged to the outside through a space formed between the support part and the opening of the object, and the support part 70 has a flow-out part 71C which allows the sterilization medium that is not discharged through the space to flow out to the outside.
