A thermoelectric generator apparatus of a vehicle may include a high temperature member, through which exhaust gas passes, a low temperature member, which maintains a temperature lower than a temperature of the high temperature member, and which includes a first coolant pipe holder supporting one of coolant pipes, a heat transfer plate which extends from the first pipe holder and may be located opposite to a corresponding high-temperature member, and a second coolant pipe holder formed on the other side of the heat transfer plate and supporting another of the coolant pipes, and a thermoelectric module disposed between the high temperature member and the low temperature member.