Forest conversion is generally associated with carbon emission. In Thailand, conversion of forests into agricultural land and other uses have reduced the total forest cover significantly in the last 50 years. The current forest area was estimated at 16 million hectares, which accounted for 31.6%. Deforestation used to be the major source of GHG emission in the LULUCF sector in 1990 (the first inventory report) with decreasing trends due to decreasing rate of deforestation. The Thailand National Forest Policy has set targets of total forest area to be 40% of the land area, of which 25% serves as conservation forest and 15% is retain as production forest. Reducing deforestation not only benefits GHG emissions, but also leads to water and soil conservation, coastal erosion protection, as well as, increasing biodiversity. Therefore, reducing deforestation is considered to be positive to sustainable development and a high priority mitigation option. REDD+ is an international mitigation measure to reduce greenhouse gas emissions from deforestation and forest degradation, and foster conservation, sustainable management of forests, and enhancement of forest carbon stocks. Thailand has been actively participating in the REDD+ readiness preparation program supported by the Forest Carbon Partnership Facility (FCPF). The program was granted in 2016 and has begun implementation. Policy related to REDD+ implementation was also acknowledged in the 11th National Economic and Social Development Plan (2012-2016). Reducing emissions from deforestation is considered to be a cost-effective mitigation measure, but there is no single cost-value for the REDD+ supply. Deerai (2011) estimated total costs for REDD+ implementation in Thailand including operating costs, transaction costs and opportunity costs. The results showed that the total costs in reducing emission by forest protection equivalent was 8.44 US$/CO. The Department of National Parks, Wildlife and Plant Conservation is the key organization implementing REDD+. The four-year action plan (2012-2015) included several programs that support REDD+ measures. For example, the Forest Conservation Program in the Yom - Nan Watershed which covers 1.74 million hectares, and the Sustainable Forest and Wildlife Resources Conservation, Protection and Rehabilitation Program, with the participation of all sectors, covers an area of 12 million hectares. All these activities are in accordance with the Strategic Plan of the Ministry of Natural Resources and Environment (