Since the REIT industry is relatively new in Singapore, the objective of this research is to examine the operation efficiency among firms in the industry through the method of Data Envelopment Analysis (DEA). In addition, the method of Tobit regression is applied to investigate the impact factors on efficiency. The results are as follows. First, none of 14 firms analyzed performs relatively efficiently based on the average efficiency scores over the sample periods of 2007 to first quarter of 2015. Nevertheless, it is found that First REIT and Suntec REIT are the most efficient and least efficient REITs respectively. Second, ROA is positively correlated to efficiency scores while the negative relationship is found with the debt ratio. Third, regarding property-type, retail REITSs perform better than commercial ones on average. However, the most efficient group is “others” which consists of one hospitality/residential REITs, one healthcare REITs, and three industrial REITs. Fourth, geographical diversification may not affect REIT’s efficiency. Meanwhile, REITs holding more properties overseas perform better than their counterparts on average. Last, in regards to size, small-size REITs significantly perform better in efficiency than those in other categories. Especially, medium-size and largesize REITs do not have significant differences on average in efficiency.