This prospective, cross-sectional, cohort observational study was conducted to evaluate the associations between sedentary behavior and arteriosclerosis-related vascular issues in community-dwelling frail older adults. We included 116 Japanese community-dwelling older adults (92 females and 24 males) who availed daycare at two long-term care insurance facilities in the cities of Yokkaichi and Handa between 2017 and 2019. An unpaired -test and the chi-square test were used for intergroup comparisons. Logistic regression analysis was conducted with cardio-ankle vascular index as the dependent variable, sedentary behavior as the explanatory variable, and the other evaluated factors as covariates. Long-time sedentary behavior (based on the median value for all participants) was associated with high cardio-ankle vascular index after adjusting for age, sex, body mass index, ankle-brachial index, and walking MET-minutes in 1 week (odds ratio 3.086, 95% confidence interval 1.275-7.467, =0.012). After adjusting for other variables (care needs certificate, skeletal muscle mass index, body fat percentage, grip strength, 4-m walking duration, etc), there was a significant association between long-time sedentary behavior and high cardio-ankle vascular index values (odds ratio 4.977, 95% confidence interval 1.497-16.554, =0.009). The results study confirmed an association between long-time sedentary behavior in frail older adults and the degree of arterial stiffness assessed by the cardio-ankle vascular index. Interventions in older adults that focus on daily sedentary time to prevent the onset and exacerbation of geriatric syndromes secondary to the progression of arteriosclerosis warrant further investigation.