While the vehicle has a wide front view, making it easy to recognize obstacles while driving, the rear side has a narrow view and the inconvenience of having to turn its head to check. A side mirror developed to address this discomfort is mounted outside the front door of a passenger car and used to identify rear objects. In this study, heat transfer analysis was performed and analyzed in order to obtain optimal defrost conditions using regression analysis method for removing mirror condensation and frost. As a result of this study, the coefficient of determination, R2, which represents the regression to the total variation through regression analysis, showed a good reliability of 85.3%. Comparing the predicted and interpreted values of the maximum temperature distribution in the regression equation established in this study, it was included in the 95% confidence interval, enabling the prediction of the maximum temperature distribution over the heat conduction time.