Air flow measuring device

A method of producing an air flow measuring device,

• the air flow measuring device including:
• a first housing that defines a bypass flow passage which takes in a part of air flowing in a duct and that includes:
• a hollow part in which the bypass flow passage is formed;
• and a recess which is formed on an upper side of the hollow part in a vertical direction of the device and at which an outer surface of the first housing is recessed inward of the first housing;
• a second housing that is formed through secondary formation with the first housing as a primary formed part, wherein:
• the recess includes side surfaces on its both sides in the vertical direction;
• and
• one of the side surfaces of the recess is located on a side of the recess that faces the second housing;
• and
• a flow sensor that is disposed in the bypass flow passage,
• the method comprising:
• providing the first housing;
• and
• forming the second housing through the secondary formation with the first housing as the primary formed part such that the first housing is held on a lower side of the second housing in the vertical direction, wherein the forming of the second housing includes inserting a part of a die into the recess to make the one of the side surfaces serve as a die cramp surface.