Purpose: This study was to identify factors affecting regular mammography screening behavior of outpatients. The target subjects were 150 women who had visited the breast clinic at the university hospital, and the study period was around 10 months from March to December 2006. Data were analyzed by using $chi^2$-test, t-test and logistic regression analysis. Results: Of the subjects, 50% experienced mammography and 31.6% took mammography regularly. In the relational analysis between various factors and regular mammography, there were significant differences among the $41{sim}50$ year old group, the employed group, the high income group, the regular exercise group, the non-drinking group, and the previously x-rayed group. And, in the Logistic Regression analysis, those who preferred bean food were 3.20 times more likely to take mammogram regularly, and those who married were 3.49 times more likely to do than the unmarried. Also, those who had low health belief and who were under age 51 were less likely to take regular mammogram. Conclusion: In order to increase the rate of conducting regular mammography, there must be different intervention strategies according to food habit, marital status and age, and a support system must be devised to increase health belief about breast cancer.