In a gas-blowing-hole array structure, which enables gas to be blown to the whole surface of the conveyed member such as a printed circuit board, a semiconductor wafer or the like almost concentrically and allows the whole surface of conveyed member to be very uniformly heated or cooled, a nozzle pattern P2 of blowing nozzles 2 is arranged to be line symmetry with a nozzle pattern P1 of the blowing nozzles 2 in upper and lower divided sections of one side of the nozzle cover 3 relative to a center portion thereof that is orthogonal to a conveying direction, as shown in FIG. 1. In order for the arrangement patterns diagonally arranged in the nozzle cover 3 to become identical, the nozzle pattern P1 is arranged to be line symmetry with the nozzle pattern P2 of the blowing nozzles 2 in upper and lower divided sections of the other side of the nozzle cover 3.