α-sialon phosphor that is α-sialon represented by a general expression: (M)x(Eu)y(Si, Al)12(O, N)16 (where M is one or more types of elements selected from a group consisting of Li, Mg, Ca, and Y as well as lanthanide element (except for La and Ce) and including at least Ca), the α-sialon phosphor being structured so that an oxygen content is 1.2 mass % or less and primary particles constituting the α-sialon have a columnar shape. When the α-sialon phosphor receives ultraviolet rays or visible light having a wavelength from 250 to 500 nm as an excitation source, the α-sialon phosphor shows a fluorescent characteristic having a peak in a wavelength region from 595 to 630 nm.