Foreign policy of a state is the manifestation of international environment phenomenom. In formulating a policy, a state is influenced by several things both from within the country and the international environment in order to deliver a decision relating the emerging issues. Rarification of Paris Agreement by government of Canada is influenced by domestic factors and international environment. Accordance to the case, this thesis will comprehensively explain the research result divided in two parts. First, this thesis will begin with William D. Coplin's theory of foreign policy in explaining domestic politics of Canada regarding the ratification of Paris Agreement, extensively on the influence of the Policy Influencer in the Canadian government. Second, this thesis will explain the theory of the international regime in demonstrating Paris Agreement as an international environmental regime in affecting Canada decission. With those explanations, we will recognize the domestic politics and international regime taking a place in influencing Canadian government under Prime Minister Justin Trudeau to involve in Paris Agreement in order to contribute in reducing greenhouse gass emissions and save the planet from climate change.