A novel immersed boundary method is introduced for simulating the fluid-structure interaction problem. Unlike the body-conforming mesh method which imposes the no-slip boundary conditions directly on the immersed interface, the immersed boundary method adopts a boundary force for the presence of the immersed solid. Therefore, the fluid is simply simulated on a fixed Cartesian mesh irrespective the movement of the immersed solid, which circumvents the mesh quality issue that frequently happens in the body-conforming mesh method. To enforce the correct boundary condition, we derive an additional moving force equation. This additional equation is integrated into a second order accurate fractional step method and solved with the conjugate gradient method. The proposed method is validated with several one-way fluid-structure interaction examples.