INTRODUCTION: Chronic constipation (CC), which can cause behavioral and psychiatric symptoms of dementia and related caregiver distress, is common in older adults admitted to care facilities with dementia. This study aimed to examine the effect of defecation care on CC and related problems. METHODS: This study compared bowel training and defecation posture intervention (intervention group) with general care (control group) as the treatment of CC among older adults with dementia in 6 long-term care facilities. The primary outcomes were the number of spontaneous bowel movements (SBMs) and complete SBMs. The secondary outcomes were Patient Assessment of Constipation Quality of Life Questionnaire, Constipation Scoring System, constipation symptoms, and Neuropsychiatric Inventory Nursing Home Version scores. The differences were analyzed using 2-way ANOVA with repeated measures. RESULTS: The data of 30 patients (14 in the intervention group, 16 in the control group) were analyzed. Weekly mean complete SBMs increased from 0.53 times at baseline to 1.58 times at 8 weeks in the intervention group compared with a change from 0.56 to 0.43 times in the control group (interaction P < 0.001). The Patient Assessment of Constipation Quality of Life Questionnaire, Constipation Scoring System, behavioral and psychiatric symptoms of dementia, and caregiver distress scores showed significant improvement after 8 weeks of defecation care intervention. DISCUSSION: Defecation care, including bowel training and appropriate defecation posture, is effective for CC among older adults with dementia, improving patient mental health and reducing burden on caregivers.