This paper presents a new method of predicting judder occurrence. In this method, the friction characteristics of the clutch, that is, the relationship between the slip speed and the friction coefficient, and torsional vibration characteristics of the drive line are both considered. Judder occurrence is judged by calculating complex eigen values of a torsional vibration model of the drive line considering the clutch friction characteristics.This method is applied to judder phenomena of automatic transmissions. Comparisons between calculations and experiments are shown. Studies of the influence of viscous damping coefficients of drive line units are also described.