This study focuses on two analysis: direct cognition of effectiveness of internship practicum, difference of career attitude maturity. The purpose of this experimental case study is to find out the practical problems of Internship education as a field-study of LIS by applying Job-Shadowing Internship methods. The results reveal that 71% of interns responded the positive effects of Job-Shadowing, but the effects to the career attitude maturity was not statistically significant. The implications of the case study are as follows; (1) systematic pre-instruction and orientation from the department are the critical factor of internship, (2) practicum guidelines(PEP), which is provided by the person in charge of tasks in internship institutions is the another important factor, and finally, (3) tools for measuring the effectiveness of internship is required for LIS practicum major course development.