A heat exchanger for a vehicle includes a heat exchange unit in which a plurality of plates are layered to alternately form a first flow channel and a second flow channel therein and heat exchange unit having one surface fixedly mounted in an expansion valve. First and second inflow holes are formed separately at both surfaces of the heat exchange unit and connected to the first flow channel and the second flow channel, respectively. First and second exhaust holes are formed separately in a diagonal direction of the first and second inflow holes at both surfaces of the heat exchange unit and connected to the first flow channel and the second flow channel, respectively. A noise reducer is integrally connected to the heat exchange unit at another surface of the heat exchange unit and reduces noise and vibration occurring when an operation fluid that is injected through the second inflow hole moves.