A bulb structure of an electrodeless lighting system comprises: a bulb body having an interior space receiving a luminous material emitting light by microwave energy; a bulb support portion integrally extending from one side of the bulb body to communicate with the bulb body, supporting the bulb body, connected to a bulb rotating motor at its one end, and having therein a passage through which the luminous material is injected; and a covering portion formed at an inner communicating portion where the bulb body communicates with the bulb support portion so as to hermetically seal the bulb body, thereby improving light distribution characteristics of the electrodeless lighting system.