Hanon Crater is the largest crater with a diameter of more than 1km and the only maar type crater in the Korean Peninsula. It is like a ‘time capsule of the Earth’s environment’, preserving the invaluable scientific information that reveals the process of the Earth’s climatic and ecological environmental changes over the past 5 million years. However, the value of the crater has been unattended and the crater itself has been damaged and neglected. About 550 years ago, as people tore down the wall of the crater to use the crater as farmland, the crater lake disappeared. In recent years, damage has been done to the crater under the threat of development without thought for the environment. This study verifies the climate and environmental value of Hanon Crater and the value of the maar lake sedimentary layers of the crater as a key national asset and the necessity of its reatoration as presented in the recommendations of the 2012 WCC and provides supportable reasons for making the restoration project as a national one in conjunction with IUCN and the international community. In particular, this study, in which the Commission on Ecosystem Management of IUCN also participated, suggests the objectives, strategies and alternatives in restoring the crater wall, lake, and vegetation based on Ecological Restoration for Protected Areas: Principles, Guidelines and Best Practices (Keenleyside et al., 2012) and ways to utilize the cater as a national resource after the restoration such as establishing a center for studying ancient organisms and climate and setting up a maar museum.”