Disclosed is a backlight device used for a color liquid crystal display (LCD) apparatus. The red light, green light and blue light, generated by a light source, made up by a red light emitting diode (21R), a green light emitting diode (21G) and a blue light emitting diode (21B), respectively, are mixed together to generate white light. The red light has a half-value width hwr such that 15 nm≦hwr≦30 nm, and the green light has a half-value width hwg such that 25 nm≦hwg≦50 nm. The blue light has a half-value width hwb such that 15 nm≦hwb≦30 nm. The white light illuminates a transmissive color liquid crystal display panel (10) from its back side. The transmissive color liquid crystal display panel includes a color filter (19) made up by a tristimulus filter for wavelength-selecting and transmitting red light, green light and blue light.