In this study, we restrict our attention to shape optimization of a body immersed in the Navier-Stokes fluid flow. The formulation and numerical results of the proposed method are presented. The proposed method is based on an optimal control theory. The optimal state is defined by the reduction of drag forces subjected to the immersed object. The cost functional should be minimized is governed by the Navier-Stokes equations. The shape sensitivity analysis of the cost functional was derived based on the adjoint method. Finally, a numerical example is given to show the feasible for the proposed algorithm.