Objectives This study sought to explore ways to substantiate process-oriented assessment so that it can be widely used in middle schools through in-depth interviews with teachers in charge of work and subjects while introducing and operating process-oriented assessment in middle schools. Methods To this end, among the student evaluation leading schools, which are policy research schools of the Seoul Metropolitan Office of Education, nine schools designated as excellent cases for three consecutive years from 2019 to 2021 were selected and operational case reports were analyzed. Four out of nine leading schools for student evaluation were selected, and in-depth interviews were conducted with teachers in charge of student evaluation at each school and teachers in charge of two subjects per school. Results Through in-depth interviews with leading schools in student evaluation by the Seoul Metropolitan Office of Education, (1) recognition of process-oriented assessment, (2) current status of operation level and system of process-oriented assessment, (3) current status of operation of process-oriented assessment, (4) student Opinions on this were identified in five aspects, including the limitations of performance in promoting process-oriented evaluation as a leading school in evaluation (5) internalization plan in the post-COVID-19 era. In addition, through the process-oriented assessment operation report, the operating grade/form/semester for each leading subject, the year of implementation, the evaluation area for each semester/subject, the strengths and weaknesses of the process-oriented assessment for each subject operated, difficulties in operating 100% performance evaluation (including mixed type) In this study, implications were drawn by diversifying the points required to vitalize process-oriented evaluation and process-oriented evaluation suitable for the nature and characteristics of the subject. Conclusions Firstly, as specified in the 2022 revised curriculum, process-oriented assessment should be continuously expanded to cultivate students' core competencies. Secondly, if the overall atmosphere of the school is created based on the clear guidelines of the Office of Education, teachers should enhance their evaluation expertise through process-oriented assessment-related training and teacher meetings (teacher learning community, subject council, etc.). Thirdly, in order to increase the rate of process-oriented assessment and continuously operate it, publicity to persuade students and parents is actively needed. Fourthly, institutional measures to reduce the workload of teachers should be prepared.