GFRP (glass fiber reinforced polymeric plastic) composite members are superior construction materials because they have higher specific strength and stiffness than steel and concretes. In addition, they also have high resistance to chemical corrosion. However, in many existing researches it reported that GFRP members have less resistance to ultra-violet ray (UV-ray), so they may cause critical structural problems due to changes of mechanical properties when the material is long-term exposed under UV-ray. In this study, we investigated whether these reports are reliable through two processes. First, we reviewed existing researches on the FRP members’s resistance to UV-ray, and then we conducted tensile strength test for GFRP sample exposed to UV-ray for 30 months (900 days). These two processes showed that mechanical properties of GFRP members do not change under long-term UV-ray exposure and they have enough resistance to UV-ray.