To provide a forgery prevention medium in which the reflection luminance can be further increased, a forgery prevention substrate including the forgery prevention medium, and a printed matter including the forgery prevention substrate.

A forgery prevention transfer foil 10 includes a diffraction grating layer 13 provided in contact with one face of a protective layer 12, and a reflective layer 14 provided on a face of the diffraction grating layer 13 on the opposite side of the protective layer 12, in which the protective layer 12 is formed of a resin containing a copolymerization structure of norbornene and ethylene.