Natural dyes have poor colorfastness as a result of the exposure of the dyed fabric to sunlight encountered during the display or wearing. As colors on fabrics fade excessively under sunlight, it is a problem to infer and restore the historic textiles with natural-dyed fabrics to original colors. The object of this study is to analyse the factors affected to color change under light. In experimental, fifteen natural dyes were dyed by the Korean traditional dyeing methods onto natural fiber fabrics: cotton, silk, ramie, and flex. Total 49 dyed fabrics in combination with dyes and fibers were used for the specimen. The Weather-O-meter was used for evaluating the effects of exposure to light for 2.5 to 450 hours. The process of color changes in the CIEL *A*B* color-order system to the exposure time were determined by spectrophotometer at 10$^{circ}$ observer. Sunlight exposure caused significant changes in the color of natural-dyed fabrics. The degree and nature of color changes on the fabrics were dependent on the combination of fiber and the type of dye used. The groups of violet(Lithospermum erythrorhizon Sieb.et Zucc.) and black color(Ailanthus altissima Swingle, Phus trichocarpa Miq) yielded excellent colorfastness to light. The group of indigo blue color(Polygonum tinctorium Lour.) was also very resistant to fading in both exposure except silk. Whereas the dye groups of Red, Yellow, Orange, Brown colors indicated greatest changes in fading, particularly Carthamus tinctorius L.