The invention has for its object the provision of an oxynitride fluorescent material has higher emission luminance than conventional rare earth element-activated sialon fluorescent materials.To this end, an oxynitride fluorescent material is designed in such a way as comprising a JEM phase as a mother crystal and a luminescence center element M1. For instance, the luminescence center element M1 is at least one kind of an element selected from Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. And the JEM phase is expressed as a general formula MA1(Si6-zAlz) N10-zOz (where M indicates a metal element, 0.1≦z≦3).