To improve a chassis structure for electronic equipment so as to reduce the size and weight of electronic equipment, to give a heat insulating function and a cooling function to the equipment, and to make the switching operation between the heat insulating function and cooling function simpler.

An electronic block or electronic circuit 1 is placed on a metallic tray 2. The tray 2 is heated with an electric heater 3. A temperature detecting circuit 4 controls the heater 3. The electronic block or electronic circuit 1 is surrounded by a heat transfer box 4 and the box 4 is covered with an insulated box 5. A heat sink 6S has such a structure that the effective heat radiating area of the plate 68 can be increased or decreased, is thermally coupled with the heat transfer box 4, and is in contact with the outside air through the wall of the insulated box 5.