Currently, predatory publishers and open access journals are flourishing in the academic field, including in the area of rehabilitation. Manca and colleagues proposed a list of suspected predatory rehabilitation journals. The purpose of this study was to assess the involvement of Japanese researchers in predatory rehabilitation journals. This study assessed and analyzed the websites of 59 predatory journals listed by Manca and colleagues. Among the 59 journals, research papers of only 39 journals could be accessed from the websites. Among these 39 journals, Japanese researchers were found to be the members of the editorial board in 16 journals and research papers by Japanese researchers were published in 24 journals. Predatory journals are threatening the field of rehabilitation research in Japan because Japanese researchers are involved in predatory rehabilitation journals. Thus, researchers should carefully select a journal when submitting a research paper.