In this paper, a simple yet effective adaptive ideal proportional navigation (AIPN) guidance law is proposed. Unlike some other approaches adopted from optimal control, two points boundary value problem is avoided. All the formulation and analysis are performed in a line of sight (LOS) fixed natural coordinate, and the closed-form solution for the case of nonmaneuvering target is derived. For the purpose of comparison, a state feedback type control law is constructed using the state-dependent Riccati (SDRE) technique. Numerical examples show that for both maneuvering and nonmaneuvering target, the proposed AIPN guidance law outperforms the IPN, and the SDRE based guidance law in the sense of time to go and defined cost