The Smoothed Particle Hydrodynamics (SPH) method is a widely used particle simulation scheme in astrophysical hydrodynamics simulations. Since a possible problem size of SPH simulations is limited by available computational resource, it is natural to implement a computation intensive core of the SPH simulations on a FPGA based reconfigurable board. We are now implementing SPH simulations on our FPGA based board PROGRAPE-3. Using our developed software, implementation of the SPH simulation becomes quite straightforward. Our "SPH processors", which compute particle interaction force by reduced accuracy floating-point operations, run at 66 MHz on our board. Obtained real performance of the SPH processors is 38 Gflops. Our results indicate using FPGA chips for floating-point intensive astrophysical simulations is being feasible.