The concept and methodology used in price asymmetry analyses can be applied on the regionalization analysis. If markets are unified and properties of crude oils are similar, price movements of the world crude oil markets should be symmetric in the cases of price increases and decreases. Accordingly, in this study, the asymmetric movements of crude oil prices were analyzed to test the degree of market integration of the world crude oil markets using the asymmetric error correction model. From the results, we could find that the degrees of market integration were estimated differently in the cases of price increases and decreases.