A thermoelectric generator apparatus of a vehicle, may include a high temperature member installed on an external wall of the exhaust pipe inside a silencer of the vehicle and exchanging heat with the exhaust gas, a low temperature member installed on the external wall of the exhaust pipe and at a side of the high temperature member, and a thermoelectric module formed by joining a P-shaped semi-conductor and an N-shaped semi-conductor, wherein the thermoelectric module may be installed on the external wall of the exhaust pipe between the high temperature member and the low temperature member so that a side thereof may be heated by the high temperature member and the other side thereof may be cooled by the low temperature member in order to use a thermoelectric phenomenon caused by a temperature difference between the side and the other side of the thermoelectric module to generate electricity.