Physical background of deformable model is described. Then, an approach of finding the contour of an object based on quantum mechanics is obtained by introducing the point of view of the quantum mechanical law of motion of a particle into extraction of object contour and estimating the probability (relative probability) that a particle goes from a point to another point. Next, Smoothing of the extracted contour is considered. Finally, this method is applied to both simulated images and real medical images.