In an intake air mass flow measurement device, for preventing clogging in a pressure intake tube due to water or the like entering the pressure intake tube in a device measuring a pressure in the intake air tube, the intake air mass flow measurement device includes a mass air flow measurement device for measuring an intake air mass flow in an intake air tube; and a pressure sensing device for sensing pressure in the intake air tube, the pressure sensing device being integrated with the mass air flow measurement device, and an aperture plane opened to the inside of a main air flow passage for detection of the pressure takes in pressure by using a gap generated between a main air flow passage constituting member and an insertion part of the mass air flow measurement device when a measurement part of the mass air flow measurement device is inserted into the main air flow passage. With this construction, it is possible to provide a structure in which water or the like can hardly clog the pressure intake port.