Abstract: A method of washing a container,including charging a material to be contained into a container body having a mouth-and-neck portion; mounting a container closure on the mouth-and-neck portion of the container body, the container closure having a top panel wall, a cylindrical skirt wall extending downwardly from a peripheral edge of the top panel wall, and a washing liquid passage formed in at least one of an upper portion of the skirt wall and a peripheral edge portion of the top panel wall; and jetting a washing liquid at the container closure so that the washing liquid passes through the washing liquid passage and enters a space between the mouth-and-neck portion of the container body and the skirt wall of the container closure, thereby washing an outer peripheral surface of the mouth-and-neck portion of the container body and an inner peripheral surface of the skirt wall of the container closure. The washing liquid is at a temperature of 65° C. to 70° C.