An endoscope plug member that is installed in an opening portion of an endoscope having the opening portion which communicates with an outside includes a first contact surface provided at the opening portion, a plug body having a second contact surface that blocks the opening portion by contacting the first contact surface, a holding portion that holds the plug body movably between a first position where the second contact surface contacts the first contact surface and a second position apart from the position, and is attachable to and detachable from the endoscope, an urging member that gives an urging force that presses the plug body in a direction in which the second contact surface contacts the first contact surface to the plug body, and an adjusting portion that selectively changes a movable range of the plug body, in the movable range of the plug body.
