The purpose of this study is to establish a weighting system for the diagnostic criteria of the KISTI Open Access Maturity Model. The maturity model consists of three dimensions, 12 sub-dimensions, and 28 measurement questions. Weighting was performed for the three dimensions and 12 sub-dimensions to determine their relative importance. The results showed that ‘Institutionalization of OA’ (48%) was the most important factor in the three dimensions. Among the sub-factors of “institutionalizing OA,” “enacting and revising relevant regulations” (64%) was important, and “financing” (39%) was important for “OA sustainability. Submission and review (23%) and author rights (22%) were identified as important elements of “journal openness”.