Background: Parallel with the rapid growth of smartphone users among the youth, its problematic use has received attention due to adverse outcomes. The psychometric properties of smartphone addiction inventory (SPAI) have been studied among Italian and Taiwanese university students. Objectives: The aim of this study was to investigate the psychometric properties of the SPAI among Iranian university students. Methods: We recruited 402 undergraduate university students in the study from February to March 2017. The SPAI and young's Internet addiction test (IAT) were completed for them. The AMOS statistical software (version 21) was used to test the five-factor model proposed in the original SPAI. The results of the goodness-of-fit index showed an ambiguous solution. For more appropriate trimming of the SPAI factorial structure, an exploratory-confirmatory cross-validation strategy was followed. Results: The SPAI showed excellent internal consistency (Cronbach's α = 0.92). Cronbach's α values of the five subscales varied from 0.53 to 0.84. The results supported a five-factor solution consisting of sleep interference, craving, daily life inference, compulsivity, and time spent (chi-square = 1105.445; P < 0.000; CFI = 0.902; TLI = 0.91; RMSEA = 0.09), which showed good convergent validity with the IAT scores. Moreover, the SPAI showed high factor correlations. Conclusions: Given the increasing trend of smartphone users in the country, the Persian version of the SAPI could be a useful tool for further investigation of smartphone problematic use among Iranian university students.