This paper describes design of tracked vehicle which can adapt rough terrain using passive link mechanism. The vehicle has two track modules at both sides which have four-bar link mechanism with passive spring elements. The passive spring elements of the link mechanism provide the restoring force which helps the vehicle to be changed to stable configuration when overcoming uneven terrains. The two track modules are connected with rotary joint so that it provides adaptability to laterally located terrain roughness. Simulating under various conditions, we verify our design concept and determine critical design parameter. We manufactured prototype vehicle with determined design parameters from simulation results. The vehicle has size of 295mm×210mm×105mm, and weight of the vehicle is 1.31kg. The prototype equips two 2.17W DC motors as driving motors. We conducted experiments with manufactured prototype under various terrain conditions. The terrain conditions include steps, stairs, trench, and unstructured terrain. In experiments, this vehicle shows good overcoming ability for the tested terrain conditions.