Advanced robotic systems have been developed to realize robot society, a mechanism and a control theory of these systems have been researched for a long time. Due to the advantages of low cost and safety, these systems with flexible mechanism are required in the future. However, the fast response of such a system which is regarded as a resonant system induces a vibration caused by mechanical resonances. Therefore, motion control theories for resonant systems have been extensively researched to improve motion response, most of these control theories are directed to the state of tip mass. This paper focuses on control theory for the position of arbitrary mass of multi-mass resonant model, proposes position control of 2-DOF resonant system. In this paper, a 2-DOF resonant system is modeled as a superposition of two-mass resonant models. The controller design is based on an assumptions; two actuators independently act on the state of middle mass, which is regarded as load. Therefore, the position control of middle mass of a 2-DOF resonant system is realized. Simulations and experiments verify the effectiveness of the proposed control theory.