To reveal the characteristics and the oral function of institutionalized frail older adults and the factors contributing to frailty. This multicenter, cross-sectional study included 214 patients. A questionnaire was administered to registered dietitians from these institutions. Sex, age, height, weight, grip strength, calf circumference, level of care need, FRAIL-NH, MNA® -SF, dysphagia, food form and water thickening, number of medications, major diseases, comorbidities, independence in daily living of older people with dementia, use of medication with dry mouth, nutritional care issues (malnutrition-related problems) by multiple occupations in Nutrition and Eating Swallowing Screening, Assessment and Monitoring, and nine oral-related items were evaluated. One hundred six patients (49.5%) were classified as frail, 75% of the patients were women, and the mean BMI was 19.7 kg/m2. Older adults with frailty were characterized by high care needs, malnutrition, multiple comorbidities, multiple medications, eating and swallowing disorders, the requirement of feeding assistance, and the need to adjust the shape of meals and fluids. The multivariable OR (95%CI) for "choking and residue problems" was 1.81 (1.20-2.73), while that for "dietary concentration problems" was 4.28 (2.10-8.74). Caregivers must maintain posture and provide meal assistance. Professionals in various occupations must adjust the proper food form and medication content. Meal times must be examined in consideration of the times at which drugs will be most effective. Oral care must be provided, and an environment must be created to help the subject concentrate. Focusing on problems of choking, residue, and concentration on meals is expected to improve frailty, aspiration pneumonia, and the prognosis of institutionalized older adults.