Purpose: The purpose of this study is to investigate the antibacterial activity Xanthium strumarium L. extract against bacteria causing eye disease and to examine the possibility as a natural preservative on behalf of synthetic preservatives which are added to the contact lens solution. Methods: Antibacterial activity of Xanthium strumarium L. extract against the bacteria causing eye disease was assessed using agar diffusion method, and determined by whether clear zone was formed around paper disc and in terms of the size(mm) of clear zone.Staphylococcus aureus and Pseudomonas aeruginosa were used in the study. Results: Xanthium strumarium L. extract provided activity against Staphylococcus aureus KCCM 40050 in a concentration of $1000{mu}g/20{mu}l$with an clear zone of 11.5 mm. Moreover, Xanthium strumarium L. extract showed an activity against Pseudomonas aeruginosa KCCM 11803 in a concentration of $1000{mu}g/20{mu}l$with an clear zone of 9.0 mm, and against Pseudomonas fluorescens KCCM 40223 with an clear zone of 7.0 mm. Conclusions: Antibacterial activity of Xanthium strumarium L. extract against the bacteria causing eye disease was proved. This result suggests that Xanthium strumarium L. extract can be a potential natural preservative, which is added to contact lens solution.