To provide an unnecessary material removing device, that the equipment and running costs are reduced and the change of set-up can easily be executed.

A folding jig fitting plate 4 vertically movable, is arranged at the upper part of a laying table 2, and a fixed plate 3 is arranged so as to be vertically movable at the center lower part of the folding jig fitting plate 4. A casting 1 is laid by fitting a work laying jig 6 for laying a product part in the casting 1 on the laying table 2, and the folding jig arranging the projections matching to the position of the unnecessary material formed in the casting 1, is fitted to the folding jig fitting plate 4, and the casting 1 is fixed by descending the fixed plate 3. Further, the unnecessary material is folded, broken and removed with the folding jig by descending the folding jig fitting plate 4.