The present invention provides image display device capable of controlling cost, improving the contrast of the display image, expanding the dynamic range and projector. Because the optical path condition from the color modulator light valve (22, 23, 24) to the relay optical system (27) is substantially the same as optical path condition from the relay optical system (27) to the brightness modulator valve (25), the light transmission prism (28) for transmitting the light from the relay optical system (27) is disposed between the relay optical system (27) and the brightness modulator valve (25),and the optical path condition is substantially the same on the both side of the relay optical system (27), so the lens which needs high design technique and has aspherical surface is need not adopted, the design of the relay optical system (27) is becoming easy. Thereby, the needed cost in designing the relay optical system (27) can be restrained.