In the past few years, the application of image tracking in laparoscopic surgery has gained popularity. In such an approach, the robot controls the movement of the laparoscope (endoscope) in surgery by following the feedback of the image tracking information. The calibration of the distorted endoscopic images is an important first step toward realizing such an approach. However, there exist very few methods for such calibration. In this paper, a new method of calibration and measurement of the endoscopic images is proposed. The high distortion of the endoscopic images makes the calibration difficult. Endoscopic images have typical barrel distortion. That is, the distortion increases as the observation becomes increasingly eccentric. We propose a new idea that only concentrates on the center area of the image. Within this area, we can ignore the complex and time-consuming distortion-correction step. A simple method for finding the intrinsic calibration parameters is then proposed. Design of a marker for the tracking task is also described. Some experimental results are presented to show the feasibility of the proposed method.