In step S106, an InXGa1-XN well layer is grown on a semipolar main surface between times t4 and t5 while a temperature in a growth furnace is maintained at temperature TW. In step S107, immediately after completion of the growth of the well layer, the growth of a protective layer covering the main surface of the well layer is initiated at temperature TW. The protective layer is composed of a gallium nitride-based semiconductor with a band gap energy that is higher than that of the well layer and equal to or less than that of a barrier layer. In step S108, the temperature in the furnace is changed from temperatures TW to TB before the barrier layer growth. The barrier layer composed of the gallium nitride-based semiconductor is grown on the protective layer between times t8 and t9 while the temperature in the furnace is maintained at temperature TB.