The purpose of this study was to investigate the effect of career decision-making self-efficacy and career attitude maturity on the relationship between career barriers and the career preparation behavior of college students. The research questions set in this study to achieve this goal are as follows. First, do career decision-making self-efficacy and career attitude maturity have a mediating effect with regard to the relationship between career barrier and career preparation behavior? Second, is there a difference in the impact on career preparation behavior for each sub-factor of the career barrier? Third, is there a difference in the effect of career barriers on career preparation behavior by gender? To answer these questions, a questionnaire was given to college students at a four-year university located in Daejeon, Korea and 224 data were collected and verified by SPSS and AMOS. The main results are as follows. First, it was found that there was a mediating effect of career decision-making self-efficacy and career attitude maturity in the relationship between career barriers and career preparation behavior. Students who perceive career barriers as high have a low degree of self-efficacy in career decision making and career maturity, and these factors lower their career preparation behavior. In addition, students with high career decision-making self-efficacy and career attitude maturity were found to be good at career preparation. On the other hand, the influence of career barrier recognition on career preparation behavior and the influence of career barriers on career preparation behavior through the mediation of career attitude maturity differed by gender. When male students feel lack of self-determination and a lack of job information, female college students experience difficulties in interpersonal relations or a lack of interest in the job, they engage in less career preparation. In addition, the mediating effect of career attitude maturity was greater in the relationship between career barrier and career preparation behavior for male students. This means that career barriers do not always act as a hindrance to career preparation behavior. In order to promote career preparation behavior during career counseling for college students, it is necessary to consider career barrier factors individually for male and female.