This paper proposes a novel method which detects a rupture of organs based on environmental impedance estimation. The proposed method detects the rupture of the organs which is conducive to serious medical accident. The environmental impedance is estimated from position and force responses of a surgery robot by using recursive least-squares algorithm. The rupture behavior is analyzed, and thresholds are settled with respect to each organ to detect the rupture. In the experiment, a two-DOF haptic surgical forceps robot which implements the bilateral control based on robust acceleration control is used. The experimental results show the effectiveness of the proposed method.