A method of manufacturing a first phosphor of which emission spectrum shape well matches with a color filter of three primary colors of light, a light-emitting device including the first phosphor, and an image display apparatus including the light-emitting device are provided. The light-emitting device includes a semiconductor light-emitting element emitting excitation light and the first phosphor absorbing the excitation light and emitting green light. The first phosphor contains a solid solution of aluminum element and a metal element M selected from the group consisting of Mn, Ce and Eu in crystals of an oxynitride having a β-type Si3N4 crystal structure, an amount of oxygen in the crystals being not higher than 0.8 mass %.