This study aims to probe into the inferior aspects in the job characteristics of career supporting practitioners (CSPs), as well as to clarify the factors related to job characteristics and career maturity, and to verify the connections thereof. In this study, career supporting practitioners are defined as “those who are actually engaged in career support in various fields, including those with qualifications.” Questionnaires were provided in which 451 responded. The results revealed that some of the main job characteristics were, “inner commitment,” “task orientation,” “coordinating the demands between the client and the organization,” “knowledge about the profession,” and “tolerance toward ambiguity.” In addition, while factors related to job characteristics and career maturity were “good scheduling” and “autonomy,” it was found that personal factors included “work experience,” “initial professional education,” and “cognitive empathy.” Organizational factors included “salary,” “support from superiors, senior staff members and supervisors” and “support from fellow workers and peers,” and intermediate factors included “role recognition” and “continuous training.” Factors varied depending on the basic attributes of the career supporting practioners. The interrelationships between the factors were also analyzed.