Objective: Social anxiety refers to an excessive concern or fear about social situations. It seems that social media, which has become one of the most popular and effective tools for communication today, can be one of the contexts of social anxiety. Due to the lack of a Persian instrument to assess social anxiety in the context of social networks, the current study was undertaken to analyze the psychometric criteria of the Iranian version of the Social Anxiety Scale for Social Media Users (SAS-SMU). The SAS-SMU is a 21-item questionnaire designed by Alkis and colleagues (2017) to measure social anxiety emerging from the social media platforms. Method : In this study, a total of 842 participants within the age range of 11 to 82 years old (mean age 33.11 ± 12.134), 59% female) answered the questions in an online survey. The original version of the scale was translated into Persian using the back translation procedure. All participants completed a Demographic Questionnaire, the SAS-SMU, and the Beck Anxiety Inventory. In order to analyze the collected data, internal and external consistency, factor analysis, construct validity, and confirmatory factor analysis (CFA) were examined. A significance level of less than 0.05 was considered to determine statistical significance. Results: Four subscales were obtained from the exploratory factor analysis (SCA, PCA, IA, and SEA), which were confirmed by the confirmatory factor analysis. Cronbach's alpha for internal consistency was found to be 0.931 for the total scale and 0.920, 0.846, 0.901, 0.828 for SCA, PCA, IA, and SEA, respectively. In addition, the test-retest scores of 30 participants (interval: between 2 to 3 weeks) for all four subscales (SCA = 0.641, PCA = 0.773, IA = 0.688, SEA = 0.727) indicated acceptable stability of the questionnaire over time. Conclusion: This study validates the Persian version of the SAS-SMU for use in studies in the field of psychological problems related to social media and online communications.