The International Committee of Medical Journal Editors (ICMJE) has published Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. These provide a global standard for writing and editing medical articles, including research integrity. However, no study has examined the research integrity-related content of Japanese medical journals' Instructions for Authors. We therefore compared research integrity content in ICMJE member journals with those in the English- and Japanese-language journals of the Japanese Association of Medical Sciences (JAMS). This was a descriptive literature study. We obtained Instructions for Authors from English- and Japanese-language journals listed on the JAMS website and the ICMJE member journals listed on the ICMJE website as of September 1, 2021. We compared the presence of 20 topics (19 in the ICMJE Recommendations plus compliance with ICMJE) in the Instructions for Authors, and analyzed the content of the conflict of interest disclosure. We evaluated 12 ICMJE member journals, and 82 English-language and 99 Japanese-language subcommittee journals. The median number of topics covered was 10.5 for ICMJE member journals, 10 for English-language journals, and three for Japanese-language journals. Compliance with ICMJE was mentioned by 10 (83%) ICMJE member journals, 75 (91%) English-language journals, and 29 (29%) Japanese-language journals. The ICMJE Conflicts of Interest Disclosure Form was requested by seven (64%) ICMJE member journals, 15 (18%) English-language journals, and one (1%) Japanese-language journal. Although the topics in the JAMS English-language journals resembled those in the ICMJE member journals, the median value of ICMJE-related topic inclusion was approximately one-third lower in JAMS Japanese-language journals than in ICMJE member journals. It is hoped that Japanese-language journals whose conflict of interest disclosure policies differ from ICMJE standards will adopt international standards to deter misconduct and ensure publication quality.