A heat exchanger for a vehicle may include a heat radiating portion provided with first, second and third connecting lines and receiving first, second, and third operating fluids respectively and a bifurcating portion connecting one of inflow holes formed to the heat radiating portion for flowing one operating fluid of the first, second, and third operating fluids with one of exhaust holes formed to the heat radiating portion for exhausting the one operating fluid, wherein the bifurcating portion may be mounted at an exterior of the heat radiating portion, and wherein the bifurcating portion bypasses the one operating fluid from the heat radiating portion according to a temperature of the one operating fluid.