A thermal type air flow meter for being placed in an intake passage of an internal combustion engine, the thermal type air flow meter comprising: a resin component; a cover member; a housing member on one side connected to the resin component and on the other side connected to the cover member; a secondary passage into which part of air passing through the intake passage can flow; a flow rate detecting element placed in the secondary passage; and a circuit board that is electrically connected to the flow rate detecting element, configured to receive an input of an amount of heat radiation from the flow rate detecting element, and configured to output a signal according to an air flow rate, wherein the resin component includes: a board fixing part comprising a surface to which the circuit board is fixed, said fixing part being a flat portion; a secondary passage constituting part which is part of the secondary passage, the secondary passage constituting part having a thickness which is larger than the thickness of the flat portion; and a reinforcing structure is provided on an outer surface of the resin component, said outer surface being arranged on a side opposite to the surface of the board fixing part to which the circuit board is fixed, characterized in that the resin component is plate-like resin molded and includes the board fixing part, the secondary passage constituting part and the reinforcing structure, and the reinforcing structure includes a plurality of ribs233, wherein the ribs 233are provided on said outer surface of the resin component and are provided in a grid-like pattern with ribs being arranged in a longitudinal direction of the resin component and ribs orthogonally crossing the longitudinally arranged ribs, and the ribs and the secondary passage constituting part protrude into the same direction to the outside of the resin component. a resin component; a cover member; a housing member on one side connected to the resin component and on the other side connected to the cover member; a secondary passage into which part of air passing through the intake passage can flow; a flow rate detecting element placed in the secondary passage; and a circuit board that is electrically connected to the flow rate detecting element, configured to receive an input of an amount of heat radiation from the flow rate detecting element, and configured to output a signal according to an air flow rate, wherein the resin component includes: a board fixing part comprising a surface to which the circuit board is fixed, said fixing part being a flat portion; a secondary passage constituting part which is part of the secondary passage, the secondary passage constituting part having a thickness which is larger than the thickness of the flat portion; and a reinforcing structure is provided on an outer surface of the resin component, said outer surface being arranged on a side opposite to the surface of the board fixing part to which the circuit board is fixed, characterized in that the resin component is plate-like resin molded and includes the board fixing part, the secondary passage constituting part and the reinforcing structure, and the reinforcing structure includes a plurality of ribs233, wherein the ribs 233are provided on said outer surface of the resin component and are provided in a grid-like pattern with ribs being arranged in a longitudinal direction of the resin component and ribs orthogonally crossing the longitudinally arranged ribs, and the ribs and the secondary passage constituting part protrude into the same direction to the outside of the resin component. a board fixing part comprising a surface to which the circuit board is fixed, said fixing part being a flat portion; a secondary passage constituting part which is part of the secondary passage, the secondary passage constituting part having a thickness which is larger than the thickness of the flat portion; and a reinforcing structure is provided on an outer surface of the resin component, said outer surface being arranged on a side opposite to the surface of the board fixing part to which the circuit board is fixed, characterized in that the resin component is plate-like resin molded and includes the board fixing part, the secondary passage constituting part and the reinforcing structure, and the reinforcing structure includes a plurality of ribs233, wherein the ribs 233are provided on said outer surface of the resin component and are provided in a grid-like pattern with ribs being arranged in a longitudinal direction of the resin component and ribs orthogonally crossing the longitudinally arranged ribs, and the ribs and the secondary passage constituting part protrude into the same direction to the outside of the resin component.