To provide high-luminance complex nitride or an oxynitride phosphor.

In the phosphor having a nitride or an oxynitride as a base, the supernatant liquid obtained by dispersing the phosphor in water, wherein the weight ratio of the water to the phosphor is 1:10, and then leaving the resulting dispersion to stand for one hour has electrical conductivity of not more than 50 mS/m. In the light-emitting device having an excitation light source and a phosphor which makes the wavelength conversion of at least part of the light from the excitation light source, this phosphor is used as the phosphor.