A reaction wheel (RW) is widely used as an actuator for controlling satellite attitude. However, the RW is a major source of an internal disturbance in a satellite. Isolation is needed for disturbance from a RW. This paper proposes the disturbance isolation platform design method for a RW which is the optimization of arranging isolator to fill the requirements for the platform design. First, the platform is modeled by the parameters of stiffness, damping, position, and the arrangement of each isolator. Next, the tolerance of the disturbance is derived from the satellite mission, and isolator parameters are designed to avoid the interference in a natural frequency of the flexible structure. As for the optimization problem, the evaluation function is formulated, and the design parameter is optimized in consideration of the tolerance of the disturbance and the amplification ratio in the natural frequency. From the simulations and experiments, it was confirmed the usefulness of the viscous fluid dumper isolator for the internal disturbance of a RW and the effect of the isolator arrangement.