PURPOSE: To contrive a decrease in the space of the title device and a reduction in the weight of the device by a method wherein the device is provided with a heat dissipation part which comes into contact with the flow of an external fluid according to the movement of a moving body, a heat pipe provided between the heat dissipation part and an apparatus and a fan or a pump for sending the external fluid to the heat dissipation part at the time of stop of the moving body.

CONSTITUTION: A cooling device for an electron apparatus and so on for aircraft is constituted of a heat pipe 2, a heat dissipation part 3, a cooling air change-over valve 7, a cooling air fan 5 and a duct 4. The part 3 is mounted on the outside of an aircraft airframe outer plate 8 and is connected to an electronic apparatus 1 in the airframe through the pipe 2. The fan 5 is installed in the duct 4, whose one end is opened outside of the airframe and which is provided in the airframe, and the other end of the duct 4 is opened in the vicinity of the part 3 and is provide so as to make the air from the fan 5 flow to the part 3. Moreover, the valve 7 is provided in the vicinity of the opening, which leads to the part 3, of the duct 4. In such a way, the heat developed in the apparatus is led out through the heat pipe and is dissipated. Thereby, the duct for a cooling fluid is shortened.