PROBLEM TO BE SOLVED: To properly sterilize a cap.SOLUTION: A cap is sterilized by spraying superheated steam (S) having pressure higher than atmospheric pressure of 200°C to 500°C made from water on at least an inner surface of a cap (1) in which hydrogen peroxide solution has placed into a cavity of the cap by a constant amount.COPYRIGHT: (C)2015,JPO&INPIT【課題】キャップを適正に殺菌する。【解決手段】過酸化水素水を一定量ずつ空洞内に入れたキャップ(1)の少なくとも内面に、水から作った200℃~500℃の大気圧よりも高い圧力の過熱蒸気(S)を吹き付けて殺菌する。【選択図】図6