The object to be processed cutting method includes: a crystal orientation identifying step of identifying a crystal orientation of the substrate; a line to cut setting step of setting, for the object to be processed, a line to cut passing through a street region formed between adjacent functional devices, after the crystal orientation identifying step; and a cutting step of cutting the object to be processed along the line to cut, after the line to cut setting step. In the line to cut setting step, in a case where an extending direction of the street region does not match the crystal orientation, the line to cut parallel to the crystal orientation and inclined with respect to the extending direction of the street region, is set for the object to be processed.