To properly remove a defective sheet material and improve operation efficiency in a defective product removal device for a box-making machine and the box-making machine.

The defective product removal device includes: a quality determination unit 101 for determining the quality of a corrugated cardboard sheet S conveyed on a production line of a corrugated cardboard box B through a predetermined inspection; a defective product removal section 51 for removing, from the production line, a corrugated cardboard sheet S having been creased on a surface thereof and slotted; and a selecting unit 102 for starting the defective product removal section 51 with respect to a corrugated cardboard sheet S determined to be defective by the quality determination unit 101.