In 2018, we conducted a study on 121 ethics review committee offices in Japan to examine the state of "central review" in non-interventional studies and discern any challenges regarding its introduction. Of the 452 offices that were invited to participate, 121 responded (26.8% response rate), and 35 (28.9%) had records of furnishing contracting agreements with ethical reviews by other research institutions. The merits of central reviewing include easing the burden on ethics review committees, improving the quality level and consistency of ethical reviews, and enhancing the efficiency in conducting them. The demerits include increased administrative overheads and work for researchers, such as preparing application forms and checking institutional requirements, and a lack of clarity regarding who is responsible for conducting the research, which makes it is less desirable for institutions to have their own ethics review committees. This study revealed that the comprehensive introduction of central review in non-interventional studies continues to encounter many hurdles, and promoting central review requires overcoming these challenges one at a time. The Ethical Guidelines for Medical and Health Research Involving Human Subjects will be revised in 2021 to require central review as a part of ethical reviews for non-interventional studies. In the future, central reviews of non-interventional studies will need to be of high quality and conducted efficiently, and this will require research institutions to utilize relevant central review guidelines and checklists.