Thailand has been influenced by the Indian Ocean Dipole (IOD), which was specified as an oscillatory mode of the anomalous sea surface temperature in the Indian Ocean. The Dipole Mode Indyex (DMI) is an indicator of the east-west temperature gradient across the tropical Indian Ocean, linked to the Indian Ocean Dipole, which is calculated as the difference between the western equatorial Indian Ocean (WTIO) and the south eastern equatorial Indian Ocean (SETIO) indices. This study uses the monthly mean rainfall data from the period 1979 to 2008, which was obtained from a total of 80 stations throughout all areas of Thailand. The relationship between the monthly mean rainfall and the DMI was investigated using the Empirical Orthogonal Function Analysis technique. The rainfall variability was extracted into a quite significant measure by the first principal component, which accounted for 57.64% of the total variance. The result from the first principal component is associated with the DMI. It shows that the event of a strong IOD affects the rainfall of Thailand.