A head lamp assembly comprising: a housing; a plurality of head lamp cases (20, 30) installed in the housing, wherein each head lamp case comprises: a case; a light emitting diode, LED, light source installed within the case; a heat sink installed within the case for dissipating heat generated from the LED light source; and characterized in that each head lamp case further comprises: a first air opening formed in one side of the case; a projection lens for emitting light forwards and formed on the other side of the case facing the first air opening; a ventilating fan installed in the case and connected to the first air opening; a second air opening formed in a bottom surface of the case; and a guide portion for guiding air introduced through one of the first and second air openings by the ventilating fan towards the heat sink and air passing through the heat sink towards the other one of the first and second air openings to emit the air out of the case, wherein the guide portion is bent from a bottom surface of the ventilating fan towards the heat sink, and further bent from the heat sink in a direction to the second air opening, and wherein the guide portion comprises a portion on which a bottom surface of the heat sink is disposed, said portion being parallel to the bottom surface of the heat sink, and the air is guided so as to flow above the guide portion. a housing; a plurality of head lamp cases (20, 30) installed in the housing, wherein each head lamp case comprises: a case; a light emitting diode, LED, light source installed within the case; a heat sink installed within the case for dissipating heat generated from the LED light source; and characterized in that each head lamp case further comprises: a first air opening formed in one side of the case; a projection lens for emitting light forwards and formed on the other side of the case facing the first air opening; a ventilating fan installed in the case and connected to the first air opening; a second air opening formed in a bottom surface of the case; and a guide portion for guiding air introduced through one of the first and second air openings by the ventilating fan towards the heat sink and air passing through the heat sink towards the other one of the first and second air openings to emit the air out of the case, a case; a light emitting diode, LED, light source installed within the case; a heat sink installed within the case for dissipating heat generated from the LED light source; and characterized in that each head lamp case further comprises: a first air opening formed in one side of the case; a projection lens for emitting light forwards and formed on the other side of the case facing the first air opening; a ventilating fan installed in the case and connected to the first air opening; a second air opening formed in a bottom surface of the case; and a guide portion for guiding air introduced through one of the first and second air openings by the ventilating fan towards the heat sink and air passing through the heat sink towards the other one of the first and second air openings to emit the air out of the case, a first air opening formed in one side of the case; a projection lens for emitting light forwards and formed on the other side of the case facing the first air opening; a ventilating fan installed in the case and connected to the first air opening; a second air opening formed in a bottom surface of the case; and a guide portion for guiding air introduced through one of the first and second air openings by the ventilating fan towards the heat sink and air passing through the heat sink towards the other one of the first and second air openings to emit the air out of the case, wherein the guide portion is bent from a bottom surface of the ventilating fan towards the heat sink, and further bent from the heat sink in a direction to the second air opening, and wherein the guide portion comprises a portion on which a bottom surface of the heat sink is disposed, said portion being parallel to the bottom surface of the heat sink, and the air is guided so as to flow above the guide portion.