Purpose: The purpose of this study was to describe the prevalence of clonorchiais and analyze the knowledge level and intention of the participants to change their behavior related to clonorchiais. Method: The participants were 514 people from 7 community health posts along the Geum River. The formalin-esther sedimentation technique was used to detect the Clonorchis Sinensis (CS) eggs and a questionnaire for data on related factors. The study was carried on from December 2008 to January 2009. Results: The prevalence of CS averaged 9.3%, with a range from 0% to 24.6%. The significant factors were sex, habit of eating raw fish, and habit related to smoking and alcohol consumption. The level of knowledge was not high and not significantly different between the CS positive group and CS negative group. Intention to change their habits of eating raw fish showed various stages of change and attitudes to raw fish eating habit of others were not positive. Conclusions: These results suggest that a CS control program needs to be developed by community health services in the Geum River area to decrease the prevalence of clonorchiais.