A projection optical system unit comprising: a reflective image display element that includes a plurality of micromirrors, the image display element having an image display surface on which the plurality of micromirrors are two-dimensionally arranged and being configured to change an angle of a reflective surface of each of the micromirrors with respect to a line normal to the image display surface to form an image; an illumination optical system configured to illuminate the image display surface; and a projection optical system comprising: a plurality of lenses and an aperture stop and being configured to magnify and project an image formed by the image display element onto a projection surface, characterized in that the projection optical system satisfies θ1 ≥ 15 deg, 3 < EP/Ym < 7, and θ2 > 30 deg, where θ1 is a maximum inclination angle of the reflective surface of each of the micromirrors with respect to the line normal to the image display surface, EP is an entrance pupil distance of the projection optical system, and Ym is a maximum distance in a plane from an optical axis to a point on the image display surface, the plane being a plane in which a light ray propagating from a center of the image display surface toward the projection surface through a center of the aperture stop of the projection optical system exists, the optical axis being an axis shared by a largest number of the plurality of lenses of the projection optical system, the point corresponding to an image on the projection surface; θ2 is an angle, with respect to the line normal to the image display surface, of a straight line connecting the center of the image display surface and a surface vertex of an optical element of the illumination optical system, the optical element being nearest to the image display surface and having power. a reflective image display element that includes a plurality of micromirrors, the image display element having an image display surface on which the plurality of micromirrors are two-dimensionally arranged and being configured to change an angle of a reflective surface of each of the micromirrors with respect to a line normal to the image display surface to form an image; an illumination optical system configured to illuminate the image display surface; and a projection optical system comprising: a plurality of lenses and an aperture stop and being configured to magnify and project an image formed by the image display element onto a projection surface, characterized in that the projection optical system satisfies θ1 ≥ 15 deg, 3 < EP/Ym < 7, and θ2 > 30 deg, where θ1 is a maximum inclination angle of the reflective surface of each of the micromirrors with respect to the line normal to the image display surface, EP is an entrance pupil distance of the projection optical system, and Ym is a maximum distance in a plane from an optical axis to a point on the image display surface, the plane being a plane in which a light ray propagating from a center of the image display surface toward the projection surface through a center of the aperture stop of the projection optical system exists, the optical axis being an axis shared by a largest number of the plurality of lenses of the projection optical system, the point corresponding to an image on the projection surface; θ2 is an angle, with respect to the line normal to the image display surface, of a straight line connecting the center of the image display surface and a surface vertex of an optical element of the illumination optical system, the optical element being nearest to the image display surface and having power. a plurality of lenses and an aperture stop and being configured to magnify and project an image formed by the image display element onto a projection surface, characterized in that the projection optical system satisfies θ1 ≥ 15 deg, 3 < EP/Ym < 7, and θ2 > 30 deg, where θ1 is a maximum inclination angle of the reflective surface of each of the micromirrors with respect to the line normal to the image display surface, EP is an entrance pupil distance of the projection optical system, and Ym is a maximum distance in a plane from an optical axis to a point on the image display surface, the plane being a plane in which a light ray propagating from a center of the image display surface toward the projection surface through a center of the aperture stop of the projection optical system exists, the optical axis being an axis shared by a largest number of the plurality of lenses of the projection optical system, the point corresponding to an image on the projection surface; θ2 is an angle, with respect to the line normal to the image display surface, of a straight line connecting the center of the image display surface and a surface vertex of an optical element of the illumination optical system, the optical element being nearest to the image display surface and having power.