This study sought to explain a political thought of Prince Wan Waithayakon on a hypothesis that he is ‘Choa’ (The Royalty) who has a progressive political thought, supports new political regime which is called that time ‘Constitutional Monarchy Regime’ and supports ‘Kha Na Rassadorn’ who did the Revolution on 1932 in Thailand and support the group which has a progressive thought like the writers, journalists for example Kuhlab Saipradid (Sri-burapa), which is different from most of ‘Choas’ who are still have a conservative political though. This thesis was used History of Political Thought approach together with contextual analysis approach to discover that what is Prince Wan Waithayakon’s political thought and what did it does or effect to Thai society.The finding were that 1). Prince Wan Waithayakon is Progressive ‘Chao’. 2). Prince Wan Waithayakon has an important role as Governmental Intellectual. 3). Prince Wan Waithayakon has a political thought as liberal democracy.