Provided is a vapor phase epitaxy apparatus of a group III nitride semiconductor capable of improving the uniformity of the film thickness distribution, and reaction rate, of a semiconductor. The vapor phase epitaxy apparatus of a group III nitride semiconductor includes: a susceptor for holding a substrate; the opposite face of the susceptor; a heater for heating the substrate; a reactor formed of a gap between the susceptor and the opposite face of the susceptor; a raw material gas-introducing portion for supplying a raw material gas to the reactor; and a reacted gas-discharging portion. In the vapor phase epitaxy apparatus of a group III nitride semiconductor, the raw material gas-introducing portion includes a first mixed gas ejection orifice capable of ejecting a mixed gas obtained by mixing three kinds, i.e., ammonia, an organometallic compound, and a carrier gas at an arbitrary ratio, and a second mixed gas ejection orifice capable of ejecting a mixed gas obtained by mixing two or three kinds selected from ammonia, the organometallic compound, and the carrier gas at an arbitrary ratio.