Background: The coronavirus disease (COVID-19) pandemic has caused unprecedented challenges for medical staff worldwide, especially for those working in hospitals in which COVID-19-positive or -suspected patients are being treated. The announcement of COVID-19 hospital restrictions by the Japanese government has led to several limitations in hospital care, including an increased use of physical restraints, that could affect the care of elderly dementia patients. However, few studies have empirically validated the impact of physical restraint use during the COVID-19 pandemic. We aimed to evaluate the impact of regulatory changes, consequent to the pandemic, on physical restraint use among elderly dementia patients in acute care hospitals.Methods: In this retrospective cohort study, we extracted the data of elderly patients (age >65 years) who received dementia care in acute care hospitals to which COVID-19-positive or -suspected patients were admitted between July 1, 2018 and June 30, 2020. We calculated descriptive statistics to compare the year-on-year trend in 2-week intervals and conducted an interrupted time-series analysis to validate the changes in the use of physical restraint.Results: The year-on-year trend in the number of patients who were physically restrained per 1,000 hospital admissions increased after the government’s announcement of COVID-19 restrictions, with a maximum incidence of 111.4% between the 47th and 48th week after the announcement. Additionally, a significant increase in the use of physical restraints in elderly dementia patients was noted (p=.002).Conclusions: Elderly dementia patients who required personal care experienced an obvious and significant increase in the use of physical restraints during the COVID-19 pandemic. Understanding the causes and mechanisms underlying an increased use of physical restraints in dementia patients can help design more effective care protocols for similar future situations.