A thermoelectric generator system of an engine is provided and includes an insulating heat protective cover that is mounted within an engine. Additionally, a unit is disposed at an upper end of the heat protective cover to uniformly distribute heat energy to use the heat protective cover mounted at an upper end of an exhaust manifold of the engine to protect a wiring from exhaust heat. Accordingly, heat energy discarded from the exhaust manifold is absorbed to generate electricity using the waste heat discarded from the exhaust manifold without affecting the catalyst to improve the fuel efficiency of the internal combustion engine. Further, heat is transferred by conduction at a particular temperature or greater and heat is transferred by radiation and convection at a temperature less than the particular temperature to increase the efficiency.