This research investigates the main factors (domestic and foreign) affecting inflation rate in Syria. Choosing the factors is based on the analysis of the major economic hypothesis concerning inflation determinants such as: excess purchasing power, cost push inflation, foreign inflation. By using OLS method, we find long run function, and it shows that the excess purchasing power has no significant effect on inflation rate. The error correction model shows that high cost rate has the biggest effect on inflation rate in the short run.