A method of growing a mixed compound semiconductor layer comprises the following steps of: providing a reaction chamber comprising a rotatable substrate stage, a plurality of nozzles aligned in a line, the nozzle being arranged vertical to a substrate surface, and a mechanism for moving the substrate stage at least in the nozzle alignment direction and parallel to the substrate surface; disposing the substrate on the substrate stage which is rotated around its axis; flowing a mixed source gas into the reaction chamber through the nozzles, thereby a flow rate of the most reactive gas in the mixed source gas flowing through each nozzle being controlled to increase depending on a distance between the center axis of the substrate rotation and the nozzle; and heating the substrate. An apparatus for applying the above method comprises a particular feature for moving the substrate stage.