Since the Ayutthaya Kingdom, Dhammaraja kingship based on Buddhis m and Devaraja kingship based on Hindu- Brahmanism had coexisted. Mos t of current studies showed that the two kingships buttressed the political au thority of kingship. While Dhammaraja kingship provided a political legiti macy to kingship, Devaraja kingship gave the divinity to kingship. And suc h studies especially emphasize that the legitimacy of Ayutthayan kingship was from Dhammaraja. Most of such studies also emphasize the negative aspects of Devaraja kin gship regarding authoritarianism, however, they did not almost clarify the Devaraja’s role on the strong goverment for the power of the state. Conside ring the trend of such current studies, my research analyzes what is the char acteristics of the two kingships using the concept of political stability, legiti macy and effectiveness. According to Lipset, the stability of any specific political system depend s on the effectiveness and legitimacy of its political system. Effectiveness i s judged according to how well the system satisfies the basic functions of g overnment as measured by reactions of most of the population and such po werful groups as business or the military forces. Legitimacy includes the ca pacity to produce and maintain a belief that the existing political institution s, or forms, are the most appropriate for the society. Lipset also insists that 태국의 탐마라차(Dhammaraja)와 테와라차(Devaraja) 특성 비교:정치적 정통성과 효율성을 중심으로 235any political system provides a plus response to both effectiveness and legit imacy are stable systems, and on the contrary, the opposing case is unstable With this hypothesis, my research focuses on why some kings were succ essful in acquiring both legitimacy and effectiveness and the others were n ot? In other words, some kings showed the plus responses to both legitimac y and effectiveness, so they became successful Dhammaraja and Devaraja. However, others showed the minus responses to both legitimacy and effecti veness, so they were not successful. This is the fundamental bases for my r esearch. Later on, I’ll explore that politically effective Devarajas without le gitimacy created political instability, legitimate Dhammaraja without politi cal effectiveness were also created political instability. The kings fall under this research are 3 kings who are King Trailokanat in the Ayutthaya Kingd om, King Taksin in the Thonburi Kingdom and Rama 1 in the Rattanakosin Kingdom.