The invention is intended to improve reliability of a thermal type air flow measuring instrument employing a molded part formed by integral molding together with a metal plate. A slot or opening allowing only a resin to pass through the same is formed in the metal plate in an area or thereabout subjected to higher stresses. A part of connector terminals, which is not required from the intrinsic object, is disposed in the vicinity of a area where the resin has a larger thickness and the temperature difference between the inside and the outside of the resin is locally increased. An injecting direction is set so as to prevent a weld line and a void from being generated in a combined way. In the molded part with the metal plate inserted therein, the occurrence of cracks and an increase of the fatigue crack growth rate can be suppressed and reliability can be improved.