Projective optical system and image projection device

An image projection device comprising a projective optical system that enlarges and projects, on a projected surface, an image that is displayed on an image display element, wherein

• the projective optical system comprises:
• a lens optical system that includes a plurality of lenses;
• and
• a transmissive optical element that has an anamorphic surface and that is provided in an optical path between the lens optical system and the projected surface, and
• the transmissive optical element has a curvature with respect to a direction that corresponds to a longitudinal direction of a display screen of the image display element, and
• on a cross-sectional surface that is perpendicular to a long side of the display screen of the image display element, and with respect to light that is emitted from the lens optical system and that is incident to the transmissive optical element,
• a light intensity of a first light flux that is incident to the transmissive optical element at a first incident angle is lower than a light intensity of a second light flux that
• enters the transmissive optical element at a second incident angle that is larger than the first incident angle.