To provide a heating device capable of preventing the deterioration of a cooking oil by the device using an electromagnetic induction principle, and capable of preventing the temperature of the cooking oil from being lowered when a large amount of ingredients of a deep-fried food is fed thereinto.

The deterioration of the cooking oil is prevented by coating a mixture of rare earth elements such as neodium for enhancing the magnetic force with a potter's clay on the whole inside surface or the bottom surface of a pan, and sintering the coated mixture at a high temperature, or laying a material obtained by sintering the mixture into a ceramic shape on the bottom surface, as an electrode, and applying an electromagnetically inductive high-frequency wave from a heating device at the lower part. The heating device has a heating structure by an electric heater, installed in the upper part of the electromagnetic induction heater, and having the function only for heating the cooking oil to prevent the reduction of the temperature when a large amount of the ingredients of the deep-fried food is fed thereinto.