Background: This study was aimed to investigate socioeconomic-related inequality in physical activity (PA) among Staff of Medical Sciences University in Shahroud, Iran.Methods: Data were extracted from the first phase of the SHAHWAR cohort study. The Concentration index (CI) and Wagstaff decomposition method were applied to determine socioeconomic-related inequality in PPA and its contributors, respectively.Results: CIs of poor total PA (PTPA) and poor work-related PA (PWRPA) were 0.092 and 0.141, indicating their more concentration among staff of higher socioeconomic groups. Furthermore, the negative CI of poor leisure-time PA (PLTPA) (-0.191) suggests that it disfavors staff from lower socioeconomic groups. While PWRPA, Subjective social status (SSS), socioeconomic status (SES), and gender were positively contributed to the measured inequality in PTPA (65.3%, 37.9%, 18.6%, and 16.6%, respectively), residence in urban areas and PLTPA have negative contributions (64% and 27%, respectively). Similarly, SES, marital status, and residence in urban areas positively contributed to the inequality of PLTPA by 53.4%, 36.2%, and 23.5% respectively. Whereas, gender had the most negative contribution by 28.7%. Residence in urban areas, SES, SSS, and shift work were all positively contributed to the measured inequality in PWRPA (its more concentration among staff from high SES groups) by 28.4%, 20%, 15.2%, and 12.7%, respectively, while the opposite is true for gender by the contribution of 13.3%.Conclusions: Different patterns of PPA inequality revealed that health promotion programs should aim to educate and support higher SES staff to increase their PA in workplace, leisure time, and transportation, and lower SES staff to increase their leisure-time PA.