Aim A increase in interarm systolic blood pressure difference (IASBPD) is believed to lead to increased risk of cardiovascular disease and to be a predictor of future cardiovascular events. The purpose of the present study was to test the hypothesis that an increased IASBPD is associated with reduced physical activity in older people. Methods Older people who used a geriatric health services facility (n = 147, mean age 83.3 years) were enrolled. The prevalence of IASBPD in individuals with different levels of physical activity and factors that have a crucial effect on IASBPD were investigated. The study participants were divided into three groups according to their physical activity; ambulant persons (group A), wheelchair users (group B) and bedridden persons (group C). Blood pressure around the both brachiums was simultaneously measured using two automated devices. An IASBPD of ≥10 mmHg was considered to be significant IASBPD. Results The median IASBPD was 4.5 mmHg in the present study participants, and 28 participants (19.0%) had an IASBPD ≥10 mmHg. The IASBPD in group C was greater than that in group A or B. Multivariate linear regression analysis showed that physical activity was the independent predictor of IASBPD after adjustment for possible factors. Furthermore, a logistic regression analysis with the end‐point of significant IASBPD showed that physical activity is an independent predictor of significant IASBPD. Conclusions Physical activity simply assessed by moving ability can predict IASBPD in older individuals. In older people, reduced physical activity might indicate the progression of silent or clinical atherosclerosis and an increased risk of cardiovascular disease. Geriatr Gerontol Int 2017; ••: ••–••.