Purpose: This study was conducted to investigate the prevalence of Clonorchiasis and factors related to it among inhabitants of the area near the Sumjin River. Method: The data were collected from December 16, 2008 to January 10, 2009. Participants were 511 people who responded to a questionnaire. The formalinesther sedimentation technique was used to detect Clonorchiasis. The data were analyzed using descriptive statistics, χ2-test with the SPSS WIN 14.0 program. Results: The prevalence of Clonorchiasis by stool examination was 21.3%. There were statistically significant differences in prevalence of Clonorchiasis by gender (χ2=5.71, p=0.017), habit of eating raw fish (χ2=13.26, p<0.001), and alcohol consumption (χ2=10.54, p=0.032). The mean score for knowledge on Clonorchiasis was 10.68 (range 0-17) and there was no significant difference between the Clonorchiasis positive group and Clonorchiasis negative group. There were statistically significant differences in intention to change their habits of eating raw fish between Clonorchiasis positive group and Clonorchiasis negative group (χ2= 26.10, p<0.001). Clonorchiasis positive group's intention was lower than the others. Conclusion: These results suggest that the prevalence of Clonorchiasis still high among the inhabitants in near the Sumjim River. Therefore, an effective management program for Clonorchiasis should be developed and administered.