Strategic Environmental Assessment (SEA) has been becoming an important tool to integrate environmental consideration into a decision-making process. It is generally understood as a process for assessing the environmental impacts caused by a proposed policy, plan and program. SEA should be recognized as a supportive method to conduct appropriative decision-making for sustainable development. In this paper, we examine the efforts toward SEA being done by local governments in Japan. Then, we focus on the SEA guideline introduced by Saitama Prefecture, overview its ideas and features, and look into a case to which the guideline was applied. The paper aims to clarify the important issues that will contribute to an effective SEA system.