A cooling device for vehicle headlights, comprising: an LED light source (11, 21) held in a housing sealed with a lens; a reflector (12, 22) that reflects a light emitted from the LED light source (11, 21); a heat sink (16, 26) that is disposed behind the reflector (12, 22); a heat pipe (14, 15, 24, 25) that transports heat generated by the LED light source (11, 21) to the heat sink (16, 26) by a working fluid encapsulated therein; characterized by a flat cuboid vapor chamber that serves as a heat collector (13, 23) on which the LED light source (11, 21) is mounted; wherein the heat sink (16, 26) is comprised of a base (16b, 26b) covering the reflector (12, 22) from behind and above while keeping a distance therebetween, and a plurality of fins (16a, 26a) erected vertically to extend from the base (16b, 26b) in the opposite side of the reflector (12, 22); wherein a surface area of lower section of the fin (16a, 26a) is smaller than that of an upper section; wherein the heat pipe (14, 15, 24, 25) includes a first heat pipe (14, 24) in which one of end portions (14a, 24a) is flattened to be contacted with a front long side of the vapor chamber, and the other end portion (14b, 24b) penetrates through the upper section of the fin (16a, 26a) while being contacted therewith, and a second heat pipe (15, 25) in which one of end portions (15a, 25a) is flattened to be contacted with a rear long side of the vapor chamber, and the other end portion (15b, 25b) penetrates through the lower section of the fin (16a, 26a) while being contacted therewith; and wherein the reflector (12, 22) is isolated from the vapor chamber and the heat pipes (14, 15, 24, 25). an LED light source (11, 21) held in a housing sealed with a lens; a reflector (12, 22) that reflects a light emitted from the LED light source (11, 21); a heat sink (16, 26) that is disposed behind the reflector (12, 22); a heat pipe (14, 15, 24, 25) that transports heat generated by the LED light source (11, 21) to the heat sink (16, 26) by a working fluid encapsulated therein; a flat cuboid vapor chamber that serves as a heat collector (13, 23) on which the LED light source (11, 21) is mounted; wherein the heat sink (16, 26) is comprised of a base (16b, 26b) covering the reflector (12, 22) from behind and above while keeping a distance therebetween, and a plurality of fins (16a, 26a) erected vertically to extend from the base (16b, 26b) in the opposite side of the reflector (12, 22); wherein a surface area of lower section of the fin (16a, 26a) is smaller than that of an upper section; wherein the heat pipe (14, 15, 24, 25) includes a first heat pipe (14, 24) in which one of end portions (14a, 24a) is flattened to be contacted with a front long side of the vapor chamber, and the other end portion (14b, 24b) penetrates through the upper section of the fin (16a, 26a) while being contacted therewith, and a second heat pipe (15, 25) in which one of end portions (15a, 25a) is flattened to be contacted with a rear long side of the vapor chamber, and the other end portion (15b, 25b) penetrates through the lower section of the fin (16a, 26a) while being contacted therewith; and a first heat pipe (14, 24) in which one of end portions (14a, 24a) is flattened to be contacted with a front long side of the vapor chamber, and the other end portion (14b, 24b) penetrates through the upper section of the fin (16a, 26a) while being contacted therewith, and a second heat pipe (15, 25) in which one of end portions (15a, 25a) is flattened to be contacted with a rear long side of the vapor chamber, and the other end portion (15b, 25b) penetrates through the lower section of the fin (16a, 26a) while being contacted therewith; and