To provide a processing method reducing the size of crack due to chipping, and suppressing foreign matter from attaching to a surface of a substrate.

The processing method comprises a step for forming a protective film 14 on the substrate 10, a step which selectively removes the protective film 14 and exposes a part of the surface of the substrate 10 as a processing area 16, a step which removes the upper part of the substrate 10 of the processing area 16 by 400 nm or more and 1,000 nm or less, and performs roughening so that an arithmetic mean roughness Ra falls in the range of 30 nm or more and 500 nm or less, and a step for forming a groove 22 on the substrate 10 by using a blade 20 in the processing area 16.