Cooling apparatus boiling and condensing refrigerant

An elongate tubular refrigerant container 2 has a barrier 5 which partitions its internal space into a heat-generating member side path 2 b and a heat radiating path 2 c , so that refrigerant vapor evaporated by the heat-generating member 3 is separated from the condensate that circulates after being cooled in the heat radiating section 4 . The barrier 5 includes a heat insulating space 5 a which does not communicate with the internal space 2 a that stores a refrigerant. The refrigerant is prevented from boiling in the heat radiating section side path 2 c and the condensate that circulates from the heat radiating section 4 and the refrigerant vapor do not collide violently with each other because the heat of the refrigerant vapor in the heat-generating member side path 2 b is prevented from being transferred to the liquid refrigerant in the heat radiating section side path 2 c.