A method of cutting an object to be processed comprises the steps of irradiating an object to be processed with a laser light which is an elliptically-polarized light having an ellipticity other than 1 such that a direction of polarization of the laser light intersects a line to cut the object and a thickness direction of the object, while locating a converging point of the laser light within the object, so as to form a modified region within the object along the line and generate a fracture from the modified region in the thickness direction of the object, and causing the fracture to reach front and rear faces of the object so as to cut the object along the line.