Characteristics of PTFE ablation due to SF6 arc exposure was studied to predict the ablated mass of PTFE nozzle in high-voltage circuit breaker. From the measurement of the ablated mass, the predominant factor of the PTFE ablation was revealed as a radiation power of SF6 arc. Subsequently, the radiation power absorbed in PTFE was formulated on the basis of the radiation transfer property and the arc physics. The formulation for the prediction of the PTFE ablated mass was established with the formulated radiation power and the measured masses. Finally, the validity of the PTFE ablated mass prediction was shown from the results of the error verification with the measured masses.