The importance of environmental laws in the developed countries has been well recognized for a long time and a number of regulations, orders and statutes are practically operated for protection of human environments. The environmental laws are firmly located as one of major laws in the legal systems of the United States. Although Korea’s environmental laws were made when those of the United States were created, different backgrounds Korea has affect from establishment of them to development and have brought about harms to environments, which are not originally intended. After several amendments of environmental laws of Korea, there is the Basic Environmental Protection Act (BEPA), which is based on the National Environmental Protection Act (NEPA) of the United States. The BEPA is to show the government’s strong intention to strengthen institutional measurements for protection of environments and among the BEPA, environmental impact assessment measurements deserves to be noticed and studied. By comparing environmental effect assessment systems between the NEPA and BEPA, I would like to have an opportunity to suggest that the BEPA would adopt better choices to protect environments.