Global Change Observation Mission (GCOM) is a follow on mission of ADEOS, ADEOS2 and TRMM. It is under phase A study in NASDA (National Space Development Agency of Japan). GCOM is not a series of satellites but a mission and its concept is to continuously monitor geophysical parameters which are critical to understand global change phenomena, especially phenomena related to climate change. Those parameters include, but not limited to, optical thickness of aerosols and clouds, water and energy fluxes, carbon fluxes, sink and source of greenhouse gases, atmospheric constituents, etc. The measurements of geophysical parameters will continue more than 15 years after the launch of ADEOS2 is now composed of 3 satellites, i.e. GOSAT (joint program of NASDA and MOE), CCOM(tentative name), and CPM core satellite (joint program of NASDA and NASA). The main target of GOSAT is to clarify the sinks and sources of greenhouse gases, especially carbon dioxide, in the continental scales by monitoring atmospheric greenhouse gases distribution. The target of CCOM is to measure geophysical parameters which are uncertain in the today’s climate models. GPM core satellite is a follow on TRMM and the target of GPM core satellite is to measure precipitation. GOSAT will carry at least 2 instruments, i.e. an instrument which can measure tropospheric carbon dioxide, and SWIFT (Stratospheric Wind Interferometer : stratospheric wind sensor). CCOM will carry three core instruments, i.e. SGLI (GLI follow on, which covers from UV to IR), AMSR2 (AMSR follow on), alpha-Scat (SeaWinds follow on). Other instruments may be added based on an AO process. GPM core satellite will carry 2 instruments, i.e. DPR (Dual Precipitation Radar : PR follow on) and a microwave radiometer. The orbit of CCOM will be a sun synchronous orbit, which is almost the same as ADEOS2. The orbits of GOSAT and GPM core satellite will be around 70 degree inclination orbit and the altitudes will be 700km and 400km, respectively. These 3 satellites are planned to be launched in 2007 and 2008. While GCOM mission is focused to global change, NASDA has other satellite series, starting from MOS-1 to JERS-1. The next satellite to follow the JERS-1 is ALOS (Advanced Land Observing Satellite), which will be launched in 2004. The mission of ALOS is to provide sufficient data, which enable to generate 1 to 25,000 scale base maps all over the world.