It is expected that the micro channel device with many narrow passages is high performance heat exchanger device in various fields, hi the present study, the heat exchanger with the micro channel device is newly manufactured by diffusion bond. Experiment and numerical analysis are performed to investigate characteristics of the heat transfer and fluid flow through the micro channel heat exchanger. It turns out that the overall heat transfer coefficient becomes high with increasing the Reynolds number of heating gas and a coolant gas. The maximum value of the overall heat transfer coefficient for gases is about 50% higher than the traditional devices.