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Objective　Stool reflect our dietary and nutritional status as well as the characteristics of gut microbiota; thus, stool can be a convenient, noninvasive index for the evaluation of physical health and nutritional intake. However, there are few studies on appropriate tools for comprehensive and easy-to-perform objective assessments of stool. Therefore, there is a need for an effective questionnaire to accurately ascertain daily bowel movement patterns ("usual evacuation") and stool characteristics. Herein, we have created an assessment tool to determine stool characteristics (volume, color, form, etc.). To investigate the validity of this tool, we compared the results with evacuation diary data wherein the participants were asked to record the number of evacuations and stool characteristics.Methods　This study included 35 adult men and women, aged 22-78 years (45.2±17.1years). A questionnaire was administered to the subjects on usual stool characteristics for the most recent month, including the average number of evacuations, stool volume per evacuation, stool color and form, stool float, and abdominal bloating. To confirm the reproducibility of each item of this questionnaire, the survey was performed twice. Thereafter, an evacuation diary was used, wherein the subjects recorded the daily number of evacuations and stool characteristics for one week. Using the evacuation diary as the valid criterion for the number of evacuations and stool characteristics, we compared responses between the diary and the usual stool questionnaire. Additionally, the questionnaire had two types of responses for the number of evacuations, namely, multiple choice for categories indicating the number of evacuations and open answers using numerical values.Results　Assessment of the reproducibility of the questionnaire on usual stool by Spearman rank correlation coefficients showed a significant correlation (ρ=0.431-0.911) for all items. The weighted κ coefficient also showed high coincidence (weighted κ=0.348-0.841). Validity was assessed by comparing the number of evacuations per one-week period between the evacuation diary and the usual stool questionnaire. A higher correlation (ρ=0.855) was observed in the open responses for the number of evacuations per one-week period. Assessment of the correlations between median values for responses to stool characteristics in the one-week evacuation diary and the usual stool questionnaire showed significant correlation (ρ=0.429-0.800) for all items except for "stool float".Conclusion　We confirmed the high reproducibility and validity of the questionnaire created in this study for the assessment of usual bowel movement patterns and stool characteristics.