A sealing structure for use on an automobile having a weather strip and an interior member wherein the weather strip includes an installation base member having an inner-cabin side wall, an outer-cabin side wall, a connecting wall and holding lips; and a seal member. The installation base member couples to a flange vertically formed along a peripheral edge of an opening corresponding to a door. The seal member is formed on the outer-cabin side wall and makes elastic contact with a door glass. The interior member is provided on an inner-cabin side of the inner-cabin side wall. An end of the interior member extends toward the connecting wall. A projection is formed on an outer circumference of a connecting part between the outer-cabin side wall and the connecting wall. The projection extends in an internal circumferential direction and covers the end of the interior member from an outer-cabin side.