An injection-molding device includes at least first and second mould parts, defining a mould cavity, wherein at least one of the mould parts includes a heating device, for heating the mould part in the vicinity of a mould cavity surface, the heating device includes an inductive coil having a plurality of windings and being powered by an oscillator. The heating device further comprises a thin top member, which functions as a susceptor for electromagnetic energy emitted by the inductive coil, which is placed in grooves in a carrier member. An intermediate member is placed between the top member and the carrier member. The intermediate member does not function as a susceptor to any grater extent, but provides mechanical stability while allowing the heat generation to be concentrated to the top member.