This study conceptualizes mentoring from social network perspective and substantiates the relationships between mentoring network characteristics, which employ the strength of ties representing the embededness called ‘bonding’ forms of social capital as well as network size and network range representing the diversity called ‘bridging’ forms of social capital, and mentoring functions, which include career, psychosocial, and role modeling functions. In addition, it explores and investigates the influences in organizational context: they imply firm size, industry, and formalization of mentoring in this study. Hierarchical Linear Model is used to examine the relationships between mentoring network characteristics and mentoring functions from mentoring networks, considering the effectiveness of organizational factors, with samples of firms and their early career employees. The results of analyses are as follows. First, tie strength has the significant and positive effects on all of three mentoring functions. Second, Network range has the negative relationship with career function and role modeling function, significantly. Third, network size is not associated with any mentoring function. Fourth, formalization of mentoring-a variable at organizational level in this study-affects career function, significantly.