To provide a mill blank for dental CAD/CAM for preparing a dental restoration by being installed in a CAD/CAM device, wherein, the mill blank for dental CAD/CAM has a substantially columnar shape, the mill blank for dental CAD/CAM has at least one recess in a circumference portion, the recess does not extend over the whole of the circumference portion of the mill blank for dental CAD/CAM, and the recess of the mill blank for dental CAD/CAM is to be engaged with the CAD/CAM device.