A built-in material scraping device for a cosmetic container is a material scraping device capable of being slipped downward with a liquid surface of liquid material stored inside the cosmetic container. An elastic piston piece is mainly into the container before a scraping element is installed on the mouth of the container, where a through hole is configured on the center of the piston piece, having a diameter equal to the diameter of a brushing rod, which is passed through the through hole to press the piston piece downward to move the stored liquid material to flow downward, thereby being convenient for the soaking of the brush head upon make-up use.