Class A shapes are used as an aesthetic standard mainly in automotive industry. Those used in products' exterior are closely related to products' values. Class A shapes have two geometric conditions: The surface has enough geometrical continuity, and smooth and continuous highlight lines. In our previous study, we developed a Class A curve generating method and style de- sign system. Using this system, an user can create a model with several Class A curves. Then, we created a model by this sys- Tem to evaluate the proposed method. Although we can create an aesthetic shape using this system, some shapes were not good in curvature variation. There is reason why some generated curves didn't produce Class A shapes. In this study, we inves- Tigate more detailed conditions of Class A curve, and improve the Class A shape generating method using Class A curve. In our new method, we extend the range of Class A conditions. By this extension, Class A shape can be generated more efficiently than the previous method. Then, we create a model using this method in order to evaluate the surface quality, and discuss the effectiveness of our system.