This study attempted to investigate the mediating effect between major satisfaction and grit in the relationship between college student’s parental attachment and career decision-making self-efficacy. To this end, a survey was conducted on 400 college students in the first, second, third, and fourth grades of universities located in the Gyeongnam area, and the data of 355 students were finally analyzed. For the collected data, structural equation model analysis was conducted using SPSS 21.0 and AMOS 21.0 programs, and Sobel verification was conducted to verify the mediating effect between each variable. The results derived through this study are as follows. First, it was found that it had a direct effect on college students’ parental attachment, grit, and major satisfaction. However, it has an indirect effect on the relationship with career decision-making self-efficacy. Second, parental attachment affects career decision-making self-efficacy through major satisfaction. Third parental attachment affects career decision-making self-efficacy through grit. Through the results of this study, stable attachment formation with parents has a positive effect on career decision-making self-efficacy that helps to achieve constant efforts and practices for individuals’ future by increasing major satisfaction in determining grit and career that can overcome long-term goals and moments of pain. Therefore, it is necessary to establish a career education system such as course, teaching resources, and learning environment to increase major satisfaction, and to develop programs to continuously maintain one’s problems and goals. In addition, this study is meaningful in verifying the need for social interest and welfare for parental education to form career classes or parental attchment that are more interesting to middle and high school students before university.