A raw material gas flows through flow channel (23) of organometallic vapor phase growing furnace (21). The raw material gas is fed in the direction traversing the principal surface (25a) of susceptor (25) from one end to another end. GaN substrates (27a-27c) are disposed on the susceptor principal surface (25a). An off angle monotonously changes on a line segment from one point on an edge of the principal surface of the gallium nitride substrates (27a-27c) toward another point on the edge. Orientation of each of the GaN substrates (27a-27c) is indicated by the direction of orientation flat. By arranging the multiple gallium nitride substrates (27a-27c) on the susceptor (25) of the organometallic vapor phase growing furnace (21) in accordance with the orientation, the influence of off angle distribution can be reduced by the use of the influence attributed to the flow of the raw material gas.