Financial relationships between pharmaceutical companies and dementia clinical practice guideline (CPG) authors are possibly biasing the recommendations in Japan. This study aimed to reveal characteristics and distribution of pharmaceutical payments made to Japanese dementia CPG authors and an extent of the transparency in the conflicts of interest disclosure among them.We retrospectively retrieved the publicly available data on payment to all the authors in the dementia CPGs by major pharmaceutical companies in Japan in 2016.The total and mean payment values from pharmaceutical companies were $880,061 and $14,427, respectively. Of the 61 authors, 49 (80.3%) physicians received at least one payment. Financial relationships of the individual authors were not disclosed in the CPGs.Pharmaceutical companies with antidementia drugs had strong financial relationships with the CPG authors. To guarantee fairness in their relationships, it is imperative to establish a framework to disclose the corporate financial conflicts of interest.