A series of captive model tests was carried out to measure the stability derivatives of an unmanned untethered submersible AUV-HM1 testbed, which has a body of a streamlined section, developed at National Taiwan University. Furthermore, for estimating its' stability derivatives, a method based on the empirical formula proposed for standard torpedoes by Bottaccini is investigated. The estimated values of stability derivatives are examined and compared with those obtained by measurement. As a result of comparison, the validity of the method is confirmed. It was also shown that the maneuverability of the submersible can be evaluated by the method with accuracy enough for practical use.