Background: Aging is often defined as a reduction in productivity, ability, and independence. A crucial step in combating ageism is to thoroughly categorize the scale of ageism through appropriate psychometric methods. Therefore, Objectives: This study aimed to evaluate the psychometric properties of the ageism scale of Yilmaz and Terzioglu. Methods: This descriptive and psychometric study was conducted on 230 (13 - 63) individuals in the fall of 2021 in Tehran, Iran, who were selected by convenient method. Construct validity was performed by exploratory and confirmatory factor analysis after the face and content validity. The tool reliability was also examined by the internal consistency and reliability method. Results: Content validity indicators for the whole questionnaire were content validity ratio (CVR) = 0.72 and content validity index (CVI) = 0.64. The KMO test rate was 0.835, and Bartlett’s test was also significant (df = 253, P < 0.001). Four factors were extracted from the exploratory and confirmatory factor analysis, including "dignity of older adults in the family," "restriction of older adults," "social presence," and "characteristics of older adults," which explained 30.57% of the total variance of ageism. The tool’s reliability was obtained using Cronbach’s alpha coefficient of 0.72 and intra-cluster correlation coefficient (ICC) = 0.94. In addition, the measurement model in confirmatory factor analysis had a moderate fit (root-mean-square error of approximation (RMSEA) = 0.081, comparative fit index (CFI) = 0.610, goodness of fit (GFI) = 0.850). Conclusions: The Persian version of the ageism scale of Yilmaz and Terzioglu had acceptable validity and reliability in the Iranian population, and it is a tool for measuring people’s attitudes toward the phenomenon of aging.