An object cutting method includes: a first step of preparing an object; a second step of irradiating the object with a laser light to form at least one row of modified regions in a single crystal silicon substrate of the object so as to extend between the at least one row of modified regions and a second main surface of the object along each of a plurality of lines to cut and to form a fracture; and a third step of, after the second step, performing dry etching on the object from the second main surface side to form a groove opening to the second main surface, along each of the plurality of lines to cut. In the second step, the modified region is formed so that a not-fracture region, to which the fracture does not extend, is formed at a predetermined position in the thickness direction in the object.