The objective of this research is to analyse and examine the influence of Theravada Buddhism on the administration of the King Lithai period. In order to find out, the most comprehensive measurement is to compare the administration of the King Lithai with the previous one. The result of the documentary research, obviously indicates that there are evolutionary changes in the role of the King, the fact is that, the role of the King has changed from the “Lord of War” to be the “Lord of Dhamma”. The main cause is an acceptance of Theravada Buddhism to be the nation’s religion. The effect of such accepted is that, there is an encouragement absolute freedom for all individuals, freedom for self-interest, freedom for sharing society’s utilities. Such freedom has been constrained by the code of conduct and morality of the society. The impact of Theravada Buddhism does effect on the basic morality of society. Norms and Values of the society are consistancy with action and seed namely “Doctrince of Karma”. It is therefore, under the King Lithai regime, the code of conduct, goodness, and goodness of mind are measurements to keep the society being in the state of peacefulness, smoothness, and progressiveness, so there is no need for any strong punitive law and order to protect the society. The knowledge which is a consequence from the studying about the ultimate goal of the society. Theravada Buddhism has described the perspective society and has divided into two levels, firstly to rebirth in coming Lord Buddha and secondly to attain Nivarna. Successfulness, depens upon how to put what Lord Buddha taught into practise. An impact of Theravada Buddhism on administration has been inherited on society’s morality, political culture since Sukothai period. Unfortunately, part of such inheritances have been ignored thus the question arises whether “Norms” and “Values” of the present society have been changed or not.
