The atmospheric-pressure plasma (APP) process is used in various fields nowadays. One important characteristic of the APP process is the temperature of the wafer heated by the atmospheric-pressure plasma. In this study, the effects of the input power and the discharge distance on the heat generated during the atmospheric plasma process were analyzed, and the mechanism was predicted. We used a fluoroptic thermometer and infrared camera to measure the wafer temperature and a VI probe and a current probe to measure the electrical properties. The results showed that, as the input power was increased, the wafer temperature increased, and as the discharge distance was increased, the wafer temperature decreased. Thus, we can confirm that resistance heating was the mechanism that caused the wafer temperature to rise; it is related to the current intensity and the resistance of the current flowing through the wafer.