Hitoshi UKAWA †a) , Nonmember and Tetsu NARUMI † †b) , Member SUMMARYThe fast multipole method (FMM) for N-body simulations is attracting much attention since it requires minimal communication between computing nodes. We implemented hardware pipelines specialized for the FMM on an FPGA device, the GRAPE-9. An N-body simulation with 1.6 × 10 7 particles ran 16 times faster than that on a CPU. Moreover the particle-to-particle stage of the FMM on the GRAPE-9 executed 2.5 times faster than on a GPU in a limited case. key words: FPGA, fast multipole method, special-purpose pipeline, Nbody simulation