The Japanese Society of the Study for Obesity defines "obesity" by the following two definitions; 1. BMI (Body Mass Index) of 25 and more. 2. Man with the waist circumference more than 85 cm and Visceral Obesity more than 100 cm², woman with the waist circumference more than 85 cm and Visceral Obesity more than 100 cm². Visceral fat can be manually calculated from the CT film but it could not be applied to the mass screening program such as health check ups where it is required to treat large volume of data. This is a principal obstacle for the introduction of CT based check up system for visceral fat. In order to solve this problem, we have developed a new software program that makes it possible to automatically calculate the waist circumference, visceral fat and subcutaneous fat form the CT imaging. In this article, the authors explain the general features of this new system.