The present invention is to provide a light emitting device which can generate high-intensity light emission, using a fluorescent material containing a rare earth element ion complex and being excellent in durability and also provide the fluorescent material to be used therein. The present invention relates to a light emitting device comprising a semiconductor light emitting element which emits light within the region from near-ultraviolet light to visible light, and a fluorescent material which contains a rare earth element ion complex having an aromatic ring-containing Bronsted acid ion with a pKa value of 7 or less as a ligand and emits light by the action of light of the semiconductor light emitting element.