To verify the efficacy of defecation care based on handheld ultrasonographic observations for functional constipation by visiting nurses skilled in bowel ultrasonography. Home-care patients with suspected functional constipation receiving nursing visits were recruited in this multiple-baseline, single-case experiment with intervention points shifted by 1 week. A total of 15 older adults were categorized into 3-, 4-, 5- or 6-week intervention phases. Ultrasonographic observations of fecal retention in the colorectum and defecation care based on observations during the ordinal physical assessment were reviewed. Tau-U was used for confirming the efficacy of the intervention by measuring the number of non-artificial and artificial defecations, as well as hard stools per week, and the amount of non-stimulant and stimulant laxatives, enemas and suppositories per week. For evaluating safety, adverse events, such as bowel obstruction and incontinence-associated dermatitis, were confirmed. No adverse events were observed. Statistical analysis showed that hard stools and artificial defecation reduced, and that their effect sizes were significant (Tau = -0.48, P < 0.01; Tau = -0.53, P < 0.01). Even the amounts of stimulant laxative and glycerin enema reduced, and their effect sizes were significant (Tau = -0.56, P < 0.01; Tau = -0.34, P = 0.04). Thus, defecation care based on ultrasonographic assessment by nurses in home-care settings is safe and effective for improving constipation symptoms and reducing laxative use. Geriatr Gerontol Int 2020; ••: ••-••.