An underwater glider is an autonomous underwater vehicle (AUV) that utilizes a small change in its buoyancy to convert vertical motions to horizontal ones with help ofwings. Thus the glider can move forward with low power consumption compared to conventional AUVs which are usually propelled by electrical motor-driven propellers. Therefore, the glider can be a small, smart and inexpensive ocean sampling platform which has a long operational time. The idea ofan underwater glider was successfully realized by Slocum, Spray and Seaglider. Slocum is the first underwater glider using thermal engine [1]. Spray has a conventional hull shape like a cylindrical body and increases payload [2]. Seaglider has a streamline hull and services sampling results in real-time [3]. Dynamic analysis and control theory have been studied to support the underwater glider. Especially, the dynamic behavior of the underwater glider needs to be studied thoughtfully. The equations ofmotion for conventional AUVs with propellers have been developed and examined intensively. In case of underwater gliders, the propulsion mechanism is quite different as mentioned above. The driving force of the glider depends on hydrodynamic forces such as drag and lift, which is a function of the advance speed and the angle of attack. Besides, the glider normally has a different control