To provide a flask inner wall cleaning scraper device, in the case the inner wall of a flask from which a mold finished with molten metal supply is drawn out is cleaned, the phenomenon that casting sand removed from the inner wall of the flask deposits on a scraper body to reduce its cleaning function does not occur.

In the case casting sand 21 stuck to the inner wall 12a of a flask 12 from which a mold 11 finished with molten metal supply is scraped off by a scraper body 19, the scraper 19 is tilted to a horizontal plane to a degree in which the casting sand 21 slides down by gravity. In this way, the phenomenon that the removed casting sand 21 deposits on the scraper body 19 to reduce its cleaning function does not occur.