At excision operations of a breast tumor, a navigation to display three-dimensional models during the operations is demanded to grasp a position and a size of the tumor, and to decide an area of the excision. Speckle noises which are characteristic of an ultrasonic image are caused by interference of sound waves. The noises cause a low resolution of a region of interest (ROI), and those are obstacle of constructing recognizable three-dimensional image. To reconstruct a three-dimensional model from two-dimensional ultrasonic tomograms, a speckle reduction and a contour extraction of the ROI are demanded. The purpose of this study is a contour extraction of a ROI on ultrasonic images. An active contour model using a gradient vector flow was employed. The contour of a lesion area of the ultrasonic images which speckle are reduced was extracted.