A red phosphor in the form of a Mn-activated complex fluoride having the formula: A2MF6:Mn wherein M is one or more tetravalent elements selected from Si, Ti, Zr, Hf, Ge, and Sn, and A is one or more alkali metals selected from Li, Na, K, Rb, and Cs, and contains at least Na and/or K, is surface treated with a treating solution containing a surface treating agent selected from an organic amine, quaternary ammonium salt, alkyl betaine or fluorochemical surfactant, alkoxysilane, and fluorinated polymer.