A laser processing method of irradiating a sheet-like object (1, 61) to be processed with laser light while locating a converging point within the object (1, 61), so as to form a modified region (17, 27, 37, 47, 67, 77, 87) to become a cutting start point in the object (1, 61) along a line to cut; the method comprising a modified region forming step of forming along the line at least a first modified region (17, 67, 57 1) located on one main face side of the object (1, 61), a second modified region (47, 87, 57 3) located on the other main face side of the object (1, 61), and a third modified region (27, 37, 77, 57 2) located between the first and second modified regions (17, 47; 57 1, 67, 87, 57 3), the first to third regions (17, 27, 37; 67, 77, 87, 57 1, 57 3) aligning in a thickness direction of the object (1, 61); the modified region forming step including the steps of: forming the first modified region (17, 67, 57 1) such that parts (17a, 67a) formed with and without the first modified region (17, 67, 57 1) alternate along a line along a first direction; forming the second modified region (47, 87, 57 3) such that parts (47a, 87a) formed with and without the second modified region (47, 87, 57 3) alternate along the line along the first direction; and forming the third modified region (27, 37, 77, 57 2) such that a part (27a, 37a, 77a) formed with the third modified region (27, 37, 77, 57 2) exists from one end side to the other end side along the line along the first direction and another line along another direction different from the first direction in the object (1, 61), characterized in that a plurality of functional devices are arranged in a matrix on the main face of the object (1, 61); wherein the lines (5a, 5b) are set like a grid between the plurality of functional devices; wherein, when the object (1, 61) is seen from a lateral side, the parts (17a, 47a, 67a, 87a) formed with the first and second modified regions (17, 47, 67, 87, 57 1, 57 3) are formed so as to exist in a part corresponding to between the plurality of functional devices (15, 65), while the parts (17a, 47b, 67b, 87b) formed without the first and second modified regions (17, 47, 67, 87, 57 1, 57 3) are formed so as to exist in a part corresponding to a center part of the functional device, wherein the plurality of functional devices each present an elongated rectangular form and are arranged in such a matrix as to have the same longitudinal direction; wherein the parts formed with and without the first and second modified regions alternate along a part of the line extending along the longitudinal direction of the functional device; and wherein the parts formed with the first and second modified regions exist between the one end side to the other end side of the object in a lateral direction of the functional device. forming the first modified region (17, 67, 57 1) such that parts (17a, 67a) formed with and without the first modified region (17, 67, 57 1) alternate along a line along a first direction; forming the second modified region (47, 87, 57 3) such that parts (47a, 87a) formed with and without the second modified region (47, 87, 57 3) alternate along the line along the first direction; and forming the third modified region (27, 37, 77, 57 2) such that a part (27a, 37a, 77a) formed with the third modified region (27, 37, 77, 57 2) exists from one end side to the other end side along the line along the first direction and another line along another direction different from the first direction in the object (1, 61),