The purpose of the present invention is to make a change in the chromaticity of an optical member due to use unlikely to occur. A method of manufacturing a prism sheet 23c as an optical member 23 to be used in a backlight unit 12 that supplies light to a liquid crystal panel 11 and transmits light from LEDs 24 as light sources of the backlight unit 12, includes a step of stabilizing the chromaticity of transmitted light by irradiation with light from chromaticity stabilizing LEDs 32 as chromaticity stabilizing light sources having a dominant emission wavelength in a blue wavelength region.