An oxynitride-based fluorescent material is formed of what results from substituting Eu for part of M of a general formula M3Si2N2O4, wherein M denotes one or more elements selected from among Be, Mg, Ca, Sr and Ba. The oxynitride-based fluorescent material can be produced by a method comprising mixing an oxide of Be, Mg, Ca, Sr, Ba or Eu, or a compound of Be, Mg, Ca, Sr, Ba or Eu enabled by heating to form an oxide, silicon nitride or a compound enabled by heating to form silicon nitride, and silicon oxide or a compound enabled by heating to form silicon oxide to obtain a mixture and firing the mixture in a vacuum or a non-oxidizing atmosphere at 1200 to 1900° C.