Objective: To evaluate the financial and non-financial conflicts of interest (COI) among authors of Clinical Practice Guideline for Obstetrics 2020 (OBCPG) and Clinical Practice Guideline for Outpatient Gynecology 2020 (GYNCPG), relationship between quality of evidence and strength of recommendations, and COI policies. Design: Cross-sectional study Setting & Populations: All 103 guideline authors of OBCPG and GYNCPG published by Japan Society of Obstetrics and Gynecology (JSOG) in 2020. Methods: Descriptive analysis and multivariate negative binomial regression analysis. Main Outcome Measures: Personal payment data from 92 major pharmaceutical companies to the OBCPG and GYNCPG authors between 2016 and 2019; and quality of evidence and strength of recommendations underlying the guideline. Results: The 66.0% of the authors received personal payments of $1,174,508 in total from 60 pharmaceutical companies between 2016 and 2019. The four-year combined average payment per author was $11,403 (standard deviation: $22,056) and the median was $2,010 (interquartile range: $0‒$8,902). For analysis of references and recommendation, a total of 50.2% of references were low quality of evidence. Only 21.4% of references were high quality of evidence. Conclusions: This study found that the 66.0% of Japanese obstetric and gynecologic CPG authors received personal payments at least once during the CPG development period. 50.2% of evidence supporting Japanese obstetric and gynecologic CPG were low quality of evidence. There were no sufficient COI policies in JSOG, as well as ACOG, comparing to the global standard COI policies for CPG development. Funding: This study was funded in part by the Medical Governance Research Institute.