The purpose of this study is to identify the effect of parentification and self–differentiation on career attitude maturity, depending on having or not having Christian beliefs, and to provide useful career counseling materials for university students. For data collection, a survey was conducted on 501 university students in Seoul and Gyeonggi, regression analysis and correlation analysis were carried out to produce results. A summary of the results of this study are as follows. First, parentification of Christian students has a negative correlation on a sub–factor of self–differentiation, emotional cutoff. Also, a sub–factor of self–differentiation, triangles, has a negative correlation with a sub–factor of career attitude maturity, preparation. As well, for non–Christian students, a sub–factor of self–differentiation, interpersonal level, had a negative correlation with parentification and a sub–factor of career attitude maturity, preparation. Secondly, for Christian students, a sub–factor of self–differentiation, intrapsychic level, independently had an effect on a sub–factor of career attitude maturity, finality; and for non–Christian students, sub–factors of self–differentiation, interpersonal level and emotional cutoff, had an effect on finality, in that order. This study emphasized the importance of inspecting the healthiness of parentified university students for relieving anxienty at the time of career counseling, and of developing a counseling strategy that helps true self–differentiation from family, environment and career attitude maturity.