Airtight lip cosmetic case of which inside is doubly sealed

An airtight lip cosmetic case of which an inside is doubly sealed, in which a lip cosmetic product inside an upper case rises and protrudes when a lower case rotates, the airtight lip cosmetic case comprising:

• the upper case rotatably coupled to an upper portion of the lower case, the upper case including a sealing shoulder formed on a lower outer circumference thereof;
• a rising piston provided in the upper case and having the lip cosmetic product attached to an upper side of the rising piston;
• a sealing piston coupled to an outer side of the rising piston and an inner side of the sealing shoulder of the upper case and having a sealing blade that extends downward from an upper outer circumference of the sealing piston;
• and
• an over-cap for opening and closing the upper case, wherein the rising piston rises in a state in which the rising piston comes into tight contact with an inner circumference of the upper case, and the sealing blade of the sealing piston comes into tight contact with an inner circumference of the sealing shoulder of the upper case,
• wherein the sealing shoulder extends downward from an outer circumference of the upper case while being spaced apart from the outer circumference of the upper case by a predetermined distance, and an upper side of the sealing shoulder is curved, and
• wherein the sealing blade is gradually inclined outward toward a bottom of the sealing piston to elastically come into tight contact with the inner circumference of the upper case.