In this paper, we prepared a far infrared ray (FIR) heater having excellent radiation characteristics, and investigated the applicable possibility in the test of breast cancer using a heating process of body surface by FIR heater. After Breast thermal images have been taken by IR camera, temperature difference and temperature rise property (dTs/dTr) were analyzed in the region of malignancy, blood vessel and normal tissue after heating 1min, 2min and 8min. From the temperature difference of malignancy-normal tissue region and blood vessel-malignancy, there was the difference according to the stage of tumor, and the significance from just before heating and after heating 1minute was found. In order to improve the discrimination of each region, dTs/dTr value was analyzed in after heating 1min. As a result, it was confirmed that dTs/dTr value is different from malignancy, blood vessel and normal tissue, and possibility of test of breast cancer was confirmed by heating process of body surface using FIR heater.