We examined the defecatory conditions in a population of Japanese subjects and analyzed the measured parameters as a means for self-evaluation of defecation. Subjects (n=1195) were residents of northern Japan and were all aged over 40 years. The state of defecation and fecal characteristics were assessed with regard to nine parameters including "self-reported bowel habit" and "bowel movement frequency." Logistic regression analysis was carried out to analyze the association between the complaint of constipation and other eight parameters. A higher tendency for constipation was noted in women than in men. The highest value of the odds ratio was "bowel movement frequency"; especially the value "once per three days or more" was noted in both genders (odds ratio: 13.38 and 42.46 in men and women, respectively). In addition, "stool appearance", "length of time for bowel movement", "straining after bowel movement", "alternating diarrhea/constipation/disorder" and "travel-related changes in bowel movements" were significantly related with the complaint of constipation ("self-reported bowel habits") in both genders. In conclusion, the study elucidated that personal and subjective evaluation of bowel habits in normal subjects consisted of various factors under the heading of "bowel movement frequency".