The objective of this study is to determine whether targeted colonoscopy skills are acquired through simulation-based training using the KAIST-Ewha Colonoscopy Simulator II, and the acquired skills can be transferred to colonoscopy to actual patients. Eleven subjects consisting of six fellows and five residents participated in the study. The fellows and residents were divided into two groups, simulation-trained group and control group. Simulation-based training included practicing the targeted skills of colonoscopy using two training scenarios with different colon flexures and degrees of difficulty. The trainees were requested to practice until they reach all the established training goals. The both groups were evaluated during their colonoscopies to actual patients, which were performed under close supervision of colonoscopy experts. The results of this study show that the developed colonoscopy simulator is effective in teaching the targeted colonoscopy skills, and transferring those skills to actual colonoscopy.