The aim of the study is to estimate the economic benefits and costs occurred to Thai service providers, consumers, labour and government in the service sectors with liberalized trade under the Japan-Thai Economic Partnership Agreement (JTEPA). This will determine which service sectors deliver maximum net benefits to Thailand in the future. Factors promoting gains and those causing losses are identified to improve the competitiveness of Thai service providers and minimize undesirable impacts. In addition, those affected adversely by the trade liberalization are revealed and appropriate assistance are recommended. Receipts to and payments by Thai public agencies due to the trade liberalization and the movement of natural persons in the service and related sectors are valued and compared. Their balance is crucial to the public finance in terms of avoiding piling public debts for Thai people as a whole.