To transmit the generated heat to a display part and to improve the heat radiation effect without using any fan motor by providing a flexible and heat transmissive heat radiation material on the top surface of a main body part or the under circuit arch surface of the display part and relatively rotating the top surface and circular arc surface while securing a contact between one of both surfaces and the heat radiation material.

The lower part of a display part 3 that is rotatively attached to a main body part 1 via a hinge part forms a circular are surface 3b which is concentrical with a rotational center 4a of the hinge part. A flexible heat radiation material 7 which improves the heat transmissivity is attached to an upper casing 1a that is opposite to the surface 3b. The surface 3b always touches the material 7 even though the part 3 rotates at any angle. The material 7 is made of an elastic material and accordingly can have a stable contact between the casing 1a and the surface 3b in a wide range and without disturbing the opening/closing of the part 3. In such a constitution, the heat of the heating parts such as a CPU 6 that is operating at the part 1 is transmitted to the part 3 and radiated in a wide area.