From the viewpoint of environmental and energy problems, there is a need to improve the thermal efficiency of internal combustion engines. We have developed a single-layer heat flux sensor using MEMS technology to quantitatively evaluate the cooling loss inside the engine. However, while this sensor succeeded in capturing high-speed heat flux fluctuations, it is not capable of measuring the DC component due to the lack of ability to measure the temperature at back surface of the sensor substrate. In this study, we proposed a double-layer thin film RTD sensor that measures the heat flux including the DC component. In this report, verifying the validity of proposed method, we conducted a preliminary experiment of the measurement of the wall heat flux using a collision jet with a commercially available Pt RTD sensor. We present the results of comparison with the single-layer sensor.