Phosphor that can provide white LED that uses a blue LED or an ultraviolet LED as a light source and that has superior luminous efficiency. This phosphor is composed of host material of β-type sialon represented by a general expression of Si 6-z Al z O z N 8-z (wherein 0.01≤z≤4.2) and includes 0.01 to 10atm% of a metal element M3, wherein M3 is one or more types of elements selected from among Mn, Ce, and Eu. Constituent particles of the phosphor have an average circularity degree of 0.75 or more, a particle size distribution D 50 of 5 to 30µm, and D 10 of 2.0µm or more. The particles of the phosphor includes light emission-related elements that have a low concentration in the interior of the particle and that have a high concentration at the outer periphery of the particle, and the light emission-related element at the outer periphery of the phosphor particle has a concentration 1.2 times or more higher than that of the light emission-related element at the interior of the particle.