Respiratory muscle strength decreases with advancing age, and respiratory muscle dysfunction may indicate respiratory sarcopenia. However, there is no consensus regarding the definition of respiratory sarcopenia. We aimed to create a definition of respiratory sarcopenia based on the peak expiratory flow rate (PEFR).Cross-sectional study.Community-based study including 681 community-dwelling older people.Body composition, spirometry, grip strength, and walking speed were measured. Participants reported comorbidities and long-term insurance certification. Conventional sarcopenia was defined using skeletal muscle mass, grip strength, and walking speed adjusted for the Japanese population. Receiver operating characteristic (ROC) curve analysis of the cut-off values of PEFR for conventional sarcopenia and long-term care insurance certification were performed for both sexes without airway obstruction. In the ROC curve analysis, potential cut-off values were lowest quartile, lowest quintiles, and the standard deviation of PEFR. Multiple logistic regression analysis was performed with respiratory sarcopenia as a dependent variable defined by each cut-off value and other variants as independent variables.The ROC curve analysis for conventional sarcopenia and long-term care insurance certification showed significance for both sexes, and we determined cut-off values from those results. The multiple logistic regression model using PEFR values 1 standard deviation below the mean had the highest accuracy; thus, we accepted these cut-off values (4.40 L/s for men, 3.21 L/s for women) for the definition of respiratory sarcopenia.The definition of respiratory sarcopenia based on PEFR was useful and correlated with conventional sarcopenia and long-term care insurance certification among community-dwelling older people. In this study, respiratory sarcopenia was determined by PEFR alone. Other parameters may need to be considered.