Abstract: This study applies the theoretical approach that views the state as a social relation to explain the political dynamics of social security policy in Thailand since the first plan aiming to provide social security to private employees and laborers introduced in the 1933 until the social security act was in force in september 1990. This study finds that the introduction and/or establishment of a social security system in each particular period was part of a broader effort to deal with and manage the tensions and conflicts that have emerged as a result of Thailand’s capitalist transition. By paying attention to the capitalist role of the state and the dynamics of such a role, this study thus provides the explanations of not only how and why social security policy has emerged and been implemented in a particular period but also how and why the roles of the thai state in the development of social security have changed over time.