A projection image display device for projecting an optical image formed by a plurality of illumination optical systems (1, 2) from a projection lens, wherein each of the plurality of illumination optical systems (1, 2) comprises: a light source (111, 211) for generating illumination light from a discharge lamp; a color separator (131, 132, 133, 231, 232, 233) for separating the generated illumination light into three color lights of red, green and blue; three liquid crystal panels (150R, 150G, 150B, 250R, 250G, 250B) for forming optical images by irradiation of the respective three color lights provided by the color separator and a color synthesis unit (160, 260) for synthesizing the optical images of the different color lights, wherein the optical axis of each of the light sources (111, 211) and the optical axis of the projection lens are positioned in the same plane, wherein all the optical axes of the respective light sources (111, 211) are oriented orthogonal to the optical axis of the projection lens, and wherein in each illumination optical systems (1, 2) of the plurality of illumination optical systems (1, 2), the optical path of the illumination light and the optical paths from the color separator (131, 132, 133, 231, 232, 233) are rotated by 90 degrees with respect to each other, characterized in that: the projection lens is formed by a single projection lens; the plurality of illumination optical systems is formed by two illumination optical systems; the two light sources (111, 211) of the two illumination optical systems are disposed to face each other in the emission direction with the projection lens downstream from them, and the projection image display device further comprises an optical synthesis unit located between the color synthesis units of the two illumination optical systems and the projection lens for synthesizing the two optical images of the two illumination optical systems, and the projection unit is located downstream of the optical synthesis unit, for enlarging and projecting the synthesized optical image. a light source (111, 211) for generating illumination light from a discharge lamp; a color separator (131, 132, 133, 231, 232, 233) for separating the generated illumination light into three color lights of red, green and blue; three liquid crystal panels (150R, 150G, 150B, 250R, 250G, 250B) for forming optical images by irradiation of the respective three color lights provided by the color separator and a color synthesis unit (160, 260) for synthesizing the optical images of the different color lights, wherein the optical axis of each of the light sources (111, 211) and the optical axis of the projection lens are positioned in the same plane, wherein all the optical axes of the respective light sources (111, 211) are oriented orthogonal to the optical axis of the projection lens, and wherein in each illumination optical systems (1, 2) of the plurality of illumination optical systems (1, 2), the optical path of the illumination light and the optical paths from the color separator (131, 132, 133, 231, 232, 233) are rotated by 90 degrees with respect to each other, characterized in that: the projection lens is formed by a single projection lens; the plurality of illumination optical systems is formed by two illumination optical systems; the two light sources (111, 211) of the two illumination optical systems are disposed to face each other in the emission direction with the projection lens downstream from them, and the projection image display device further comprises an optical synthesis unit located between the color synthesis units of the two illumination optical systems and the projection lens for synthesizing the two optical images of the two illumination optical systems, and the projection unit is located downstream of the optical synthesis unit, for enlarging and projecting the synthesized optical image. the projection lens is formed by a single projection lens; the plurality of illumination optical systems is formed by two illumination optical systems; the two light sources (111, 211) of the two illumination optical systems are disposed to face each other in the emission direction with the projection lens downstream from them, and the projection image display device further comprises an optical synthesis unit located between the color synthesis units of the two illumination optical systems and the projection lens for synthesizing the two optical images of the two illumination optical systems, and the projection unit is located downstream of the optical synthesis unit, for enlarging and projecting the synthesized optical image.