The present invention relates to a phosphor comprising a nitride or an oxynitride, comprising an X-ray powder diffraction pattern comprising at least one Region having at least one peak with an intensity ratio I of 8% or less, the X-ray powder diffraction pattern measured in the 2θ range from 10° to 60° using a CuKα line (1.54184 {acute over (Å)}), wherein the Region is the 2θ range from 41.5° to 47°, the intensity of each peak is a value obtained after background correction, and the intensity ratio I is defined by the formula (Ip×100)/Imax (%), where Imax represents the height of the most intense peak present in the 2θ range from 34° to 37° and Ip represents the height of each peak.