A device which measures a physical quantity of a gas flowing through a main passage is described. The device includes a flange for fixing to the main passage; a housing that protrudes toward an inside of the main passage from the flange; and a printed circuit board fixed to the housing on which a measuring element that measures the physical quantity is mounted. Wiring of the printed circuit board has a plurality of irregularities formed along one direction of a surface, and the wiring is arranged such that a formation direction of the irregularities is oriented along a protruding direction of the housing toward an inside of the main passage. The irregularities may be polishing marks formed using a cylindrical polishing wheel or rolling marks of the wiring of the printed circuit board.