The present invention provides a novel structure for sealing a cosmetic container using a double-injection molded rib on the container body sealing against a deformable hard-rubber ring on the container cover. The invention will maximize product reliability by improving the sealing structure of a make-up base or cosmetic container through providing a clear, air-tight effect since the sealing structure cannot be deformed, even in the case of long-term use. The invention provides uniform, airtight adhesion without unequal distribution of coupling intensity between internal sealing components when the container cover is closed. Further, the aesthetics of the container are increased because a closure clasp is not necessary, and it is possible to eliminate the problem of dried-out product created when the container is fitted with a closure clasp or similar device.