Tourism has recently played a significant role to the economic development of Thailand. Tourists pay great contributions to economic growth as well as income distribution. Furthermore, tourists also help country maintaining a surplus in its balance of payments. Thus, tourism study is considered as an important and significant guideline for Thailand's tourism development. The purpose of this study is to clarify which factors have impacts toward tourist expenditures. The study has selected the first and the second countries from each region, which contributed more than 3% of total income from tourists for Thailand. They are Australia, England, Germany, Japan, Malaysia and United States.