A cutoff device with a liquid bag includes a framed housing that supports a cover having a cutoff wall. The cutoff wall is opened at a lower end thereof with a liquid bag attached along the opened lower end of the cutoff wall. The housing includes telescopic columns, upper support frames coupled to the upper ends of the telescopic columns, and a lower support frame coupled to the lower ends of the telescopic columns. The upper end of the liquid bag may be fastened to the opened lower end of the cutoff wall using a zipper. The liquid bag contains liquid, such as water, therein, with a heavy substance, such as sand, soil and powdered or granulated metal, added to the liquid.