To provide a thermal flow sensor capable of inhibiting fluctuation of sensor characteristics due to a change in temperature.

The thermal flow sensor includes a sensor chip having a sensing part containing a heater provided on a void region of a substrate via an insulation film and a supporting member to which the sensor chip is fixedly stuck. The sensor chip is fixed to the supporting member with part of a rear face of a heater arrangement surface of the substrate which is part of a region separate from the void region serving as an adhesive region with an adhesive member. A notch opening at least on one of a surface and a rear face of the substrate is formed separately from the void region on a region located between the heater of the sensor chip and the adhesive region on the substrate.