PURPOSE: To ensure the heat reserving ability of a container and to reduce the weight of a body.

CONSTITUTION: An outer shell of a container 1 is formed of a heat reserving layer 5 which is provided at its inner surface with a heat generating layer 4 and which defines a space layer 11 between itself and an inner frame 3. Besides, a coil 15 for induction-heating the heat generating layer 4 is provided at the outer surface of the inner frame 13. With this arrangement, the heat reserving layer 5 prevents the container 1 from lowering its temperature even though the induction heating is stopped. Further, the space layer 11 restrain the inner frame 13 from increasing its temperature even though the temperature of the heat reserving layer 5 rises up to a high value. Accordingly, the inner frame 3 may be formed from a plastic material having a low density.