Disclosed is an electrodeless discharge lamp in which high output can be achieved by enhancing heat dissipation properties. The electrodeless discharge lamp comprises a bulb filled with discharge gas,and a coupler contained in a cavity formed in the bulb for generating a high frequency electromagnetic field. The coupler has an induction coil, a core inserted into the coil, a heat conductor for conducting heat generated from the coil and the core, and a resin bobbin for containing the core and the heat conductor and around which a coil is wound. Since the bobbin can be dismantled in the radialdirection of the coil, each part of the bobbin can be molded separately. Consequently, a draft required conventionally when a tubular bobbin is molded can be eliminated, the bobbin can be made thinner uniformly, and the ratio of the heat conductor can be increased by reducing the occupation rate of the bobbin in the volume of the cavity.