In the 1950’s, Dr. Inoue measured CO2 flux above a rice paddy. This was made by the gradient method, whereas one of the first CO2 flux measurements in the world. Dr. Mitsuta and Dr. Ohtaki made a major contribution toward the application of the eddy covariance technique. Dr. Mitsuta put sonic anemometer/thermometer (SAT) into practical use, and Dr. Ohtaki developed an open-path infrared gas analyzer for CO2 and water vapor. Based on their technical support, Japanese companies made SATs and open-path analyzers, but unfortunately the open-path analyzer now goes out of production. In the 1990’s, long-term flux monitoring began also in Japan. Dr. Yamamoto started flux monitoring at Takayama site, a deciduous broad leaf forest, in 1993. Takayama site is the oldest tower site with the longest record in Asia, also one of the oldest sites in the world. In 1999, Forestry and Forest Products Research Institute (FFPRI) established a local flux network with 5 forest sites in Japan. In the following year, National Institute for Environmental Studies (NIES) launched flux monitoring at Tomakomai site, a larch forest. At present about 30 flux monitoring sites are active at some types of forest, grassland, rice paddy and wetland in Japan. Using data collected at these flux sites, we will report the carbon balance of typical terrestrial ecosystems in Japan.