To automate the input operation of a rack number performed by an operator.

When setting the rack number for material rack control information added to NC data, rack information containing the names and thickness of materials stored on the respective racks of a material rack is registered in rack information storage parts 31 and 32, corresponding to the rack numbers of respective racks. When designating the NC data, on the basis of the material name and the thickness contained in these NC data, the rack information registered in the rack information storage parts 31 and 32 is retrieved and a rack number having the same rack information as the material name and the thickness is acquired. Then, this acquired rack number is set as a rack number for material rack control information to be added to the designated NC data.