Provided is a sheet 2 for forming a protective film including a protective film-forming film 1 of which the light transmittance at a wavelength of 1600 nm is 25% or greater, and light transmittance at a wavelength of 550 nm is 20% or less, and a release sheet 21 which is laminated on one or both surfaces of the protective film-forming film 1. According to such a sheet 2 for forming a protective film, cracks existing in a workpiece or a manufactured product obtained by processing the workpiece can be inspected and a protective film in which grinding marks existing in the workpiece or the manufactured product are not visually recognized can be formed.