In an electrodeless lighting system having a cooling unit for cooling a radiator therein, the electrodeless lighting system includes a microwave generating unit for generating microwave energy; a light emitting unit connected to the microwave generating unit and emitting light by forming plasma by the microwave energy generated in the microwave generating unit; a housing having a first receiving space for receiving the microwave generating unit and sealed-combined with the light emitting unit; a heat exchanger installed at the outer surface of the microwave generating unit to absorb heat generated in the microwave generating unit; a radiator installed at the outer surface of the housing; and a heat transfer member at which one end is connected to the heat exchanger and the other end is connected to the radiator by penetrating the housing to transmit heat from the heat exchanger to the radiator.