A MEMS flow sensor, an electrical wiring, and a flow tube structure were integrated onto the same substrate, for the first time. A Cu on polyimide (COP) was used as the sensor substrate. First, both sensor devices composed of a heater working as flow velocity sensor and a temperature sensor, and electrical wiring were fabricated in the same substrate. The signal lines in the sensor device were automatically connected to the electrical wiring formed into the Cu layer during the fabrication to eliminate an electrical bonding process. Finally, the tube structure was successfully integrated with the same substrate of the sensor device and the wiring to deform a part of COP substrate plastically. Flow detection and response time of fabricated flow sensor were evaluated as the basic characteristics. Besides, it was applied in the breathing flow measurements in rat, as one of the applications, and the breathing airflow at the rat was directly detected.