Disclosed herein is a processing method for forming a plurality of quadrangular prisms on a plate-shaped substrate having a product area. The processing method includes the steps of preparing an excess-sized plate-shaped substrate having an excess area surrounding the product area, cutting the excess-sized plate-shaped substrate in a first direction by using a cutting blade to thereby form a first cut groove extending in the first direction, cutting the excess-sized plate-shaped substrate in a second direction perpendicular to the first direction by using the cutting blade to thereby form a second cut groove extending in the second direction, filling the first cut groove and the second cut groove with a resin, and cutting the excess-sized plate-shaped substrate along the boundary between the product area and the excess area by using the cutting blade to thereby remove the excess area from the excess-sized plate-shaped substrate.