This paper presents a control method to achieve stable landing to rough and unknown terrain. Landing control is one of the important issues for biped walking robot, because robots are expected to walk on not only flat known surfaces but also unknown and uneven terrain to contribute to human society. A point-contact type foot with spring is employed in this control method, and it realizes stable contact with rough terrain and suppression of impact force. The proposed controller can adjust the foot position and posture without excessive impact by using the reaction force and torque estimated from the spring displacement, and guarantee the robust stability of control system with respect to terrain variance. The effectiveness of the proposed controller is demonstrated by experimental results.