Purpose: This study was done to evaluate factors affecting active early detection behaviors of breast cancer and performance rate of breast self examination (BSE), physical examination and mammography. Methods: The participants were 264 women from an outpatient breast clinic of a university hospital and materials were collected from March 2007 to February 2008 using a structured questionnaire. The data were analyzed using $x^2$ test, logistic analysis. Results: The rate for BSE was 58.3%, for physical examination, 55.3% and for mammography experience, 63.4%. Women with all of these active early detection behaviors accounted for 31.8% of the participants. Various factors such as age, income, marital status, and menopause showed increased significant performance rate. The explanation power of logistic model was 48.5%, and was significant for age, income and health belief. Factors related to high performance rate were being over 40 years of age, high income and high health belief score. Conclusion: Active early detection behaviors were not high in spite of marked increases in breast cancer incidence. Encouragement for women practicing early detection behavior is important, but there is also a need to develop interest and support for the low performance group. More sustained education and public relations are needed to further improve active early detection behavior.