To provide a photomask installed on a normal contact exposure apparatus or a proximity exposure apparatus in parallel to an irradiation object body without any necessity of inclining the irradiation object body, and capable of performing diagonal exposure with a plurality of different angles by a single exposure to the irradiation object body.

The photomask emits parallel light that is perpendicular to the photomask and emitted by an exposure apparatus, to an irradiation object body in an inclined manner. The photomask includes a diffraction optical element formed on the irradiation surface side of a transparent substrate, and a pattern of a light transmission part that selectively transmits diffraction light from the diffraction optical element, formed on an emission surface side of the transparent substrate.