The application of cubic spline is presented for basic curve (DRD motion) of cam motion. The purpose of this paper is to achieve better dynamic characteristics than general cam curves. A cubic spline is a piecewise function that is continuous in displacement, velocity and acceleration. The best cam curve is obtained by changing the weights of the object function. So the method can be used to any machine system case by case. For the proposed object function, the result has improved all characteristics such as velocity, acceleration and jerk compared with that of the modified sine curve.