The purpose of this study is to investigate the mediating effect of ocuupational value in the relationship between University students motivation for choosing a major and career preparation behavior. To this end, a survey was conducted on 337 university students in the first, second, and third grades of the university, of which 264 valid questionnaires were used for the study. The data collected through the survey were statistically analyzed using the IBM SPSS 26.0 program, and mediated regression analysis was performed using Hayes' process macro model 4 to verify the research hypothesis. As a result, first, it was confirmed that the motivation for selecting a major had a significant positive (+) effect on ocuupational values. Second, the total effect of major selection motivation on career preparation behavior was confirmed without considering ocuupational value, and as a result, major selection motivation had a positive (+) effect on career preparation behavior. Third, the mediating effect according to the sub-factors of ocuupational value was confirmed in the effect of major selection motivation on career preparation behavior. To this end, the effect of major selection motivation and job value on career preparation behavior was confirmed by inputting both major selection motivation and job value, and as a result, it was found that major selection motivation had a positive (+) effect on career preparation behavior, but job value did not. In other words, as a result of bootstrap verification to verify the mediating effect of ocuupational value, it was found that ocuupational value did not mediate the effect of major selection motivation on career preparation behavior. However, as a result of verifying the mediating effect of the sub-factors of job value, it was found that intrinsic ocuupational value (attitude, achievement, ability) mediates the influence of intrinsic motivation (attitude, interest, talent, and future) on career preparation behavior. This indicated that intrinsic ocuupational value can make specific career decisions and active career preparation actions by improving career search activities. As a result of this study, it was found that when intrinsic ocuupational value are satisfied, the motivation for choosing a major leads to career preparation behavior more. Therefore, people in charge of the university field need to diversify the direction of career education and support according to the students' personal characteristics and motivation for choosing a major. Therefore, it is expected that this study will be used as basic data for counseling and education that can establish ocuupational value and increase career confidence for students' active career preparation behavior from the lower grades of university.