The Science and Technology Agency of Japan has proposed a project to promote studies for global change prediction by an integrated three-in-one research and development approach: earth observation, basic research, and computer simulation. As part of the project, we are developing an ultra-fast computer, the “Earth Simulator”, with a sustained speed of more than 5 TFLOPS for an atmospheric circulation code. The “Earth Simulator” is a MIMD type distributed memory parallel system in which 640 processor nodes are connected via fast single-stage crossbar network. Earth node consists of 8 vector-type arithmetic processors which are tightly connected via shared memory. The peak performance of the total system is 40 TFLOPS. As part of the development of basic software system, we are developing an operation supporting software system what is called a “center routine”. The total system will be completed in the spring of 2002.