In the present study, aeroelastic response of HART II rotor blade has been numerically investigated using a coupled CFD/CSD method. Aerodynamic forces were calculated from a Navier-Stokes CFD flow solver based on unstructured mixed meshes. In the mixed meshes methodology, body-fitted prismatic/tetrahedral mesh was used in the near-body flow region to handle complex geometries easily. Cartesian mesh was used in the off-body flow region and high-order accurate weighted essentially non-oscillatory scheme was employed to implement high-order spatial accuracy. In the FEM-based CSD solver, an elastic deformation of the rotor blade was obtained on the basis of nonlinear Euler-Bernoulli beam theory. The coupling between the CFD and CSD solver was performed in a loosely coupled manner by exchanging the aerodynamic loads and elastic deformation of the rotor blade. An overset mesh technique was adopted to simulate rotating motion of the rotor blade and to exchange flow information between two different meshes. In addition, spring analogy was used to implement elastic deformation of the rotor blade. Coupled CFD/CSD method was applied to the HART II rotor in forward flight to examine aerodynamic performance and aeroelastic effect of the rotor. Aerodynamic loads and elastic deformation of the rotor blade were calculated and compared with experimental results and other research efforts. Overall, the present results were in good agreement with the experimental data. In addition, adaptive fine mesh was used to capture tip vortex trajectory and BVI (blade-vortex interaction) phenomenon more accurately.