To provide a gable wall panel units for which a high workability on the job site and a high accuracy can be obtained even by unskilled workers in forming the gable wall.

These are panel units for constituting a gable wall directly below the roof of gable roof and each unit is a board member formed to a polygonal shape; and by jointing together these side portions, these units are equipped with a plurality of exterior wall panels 18, 19 and 20 directly below the roof aligned with the slope of the gable roof and also with a plurality of panel reinforcing cross members 21 to 32 fixed in advance to the rear side of these exterior wall panels 18, 19 and 20.