A projector , comprising: a light source ; an image forming unit including an image generating device illuminated with light emitted from the light source to generate an optical image; a projection optical unit including optical devices to project the optical image generated by the image forming unit ; a power supply to supply electric power to the light source ; a case that contains the light source , the image forming unit , the projection optical unit , and the power supply , the case having an upper surface including a window through which the projection optical unit projects the optical image and at least first and second side surfaces that are perpendicular to the upper surface and to each other; a first intake duct provided in the case ; and a second intake duct provided in the case , wherein the projector takes first outside air into the case through the first intake duct provided on the case , flows the first outside air around the projection optical unit to the power supply to cool the power supply , takes second outside air into the case through the second intake duct to cool the power supply, and exhausts the fist and second outside air after cooling through an exhaust vent provided on the case , characterised in that an amount of outside air drawn into the case through the second intake duct is larger than an amount of outside air drawn into the case through the first intake duct ; the first intake duct is provided in the first side surface; the second intake duct is provided in the second side surface closer to the power supply than the first intake duct ; and wherein the total cross-sectional area of the second intake duct opening is larger than 300 mm 2 . a light source ; an image forming unit including an image generating device illuminated with light emitted from the light source to generate an optical image; a projection optical unit including optical devices to project the optical image generated by the image forming unit ; a power supply to supply electric power to the light source ; a case that contains the light source , the image forming unit , the projection optical unit , and the power supply , the case having an upper surface including a window through which the projection optical unit projects the optical image and at least first and second side surfaces that are perpendicular to the upper surface and to each other; a first intake duct provided in the case ; and a second intake duct provided in the case , wherein the projector takes first outside air into the case through the first intake duct provided on the case , flows the first outside air around the projection optical unit to the power supply to cool the power supply , takes second outside air into the case through the second intake duct to cool the power supply, and exhausts the fist and second outside air after cooling through an exhaust vent provided on the case , characterised in that an amount of outside air drawn into the case through the second intake duct is larger than an amount of outside air drawn into the case through the first intake duct ; the first intake duct is provided in the first side surface; the second intake duct is provided in the second side surface closer to the power supply than the first intake duct ; and wherein the total cross-sectional area of the second intake duct opening is larger than 300 mm 2 . <EOS>