To provide cooked and processed eggs which are preservable for many hours and have improved taste by heat treatment with warm air by heated compressed air generating a terahertz wave-like resonant electromagnetic wave and a method for producing the same.

The bird eggs such as hen's eggs, etc., maintaining freshness for a long period of time and an improved taste are obtained by contacting eggs with heated compressed air generating a terahertz wave-like resonant electromagnetic wave by adjustment to regulated pressure and temperature and heat-treating the eggs for a fixed time to form solid solutions of egg white and egg yolk. The method for producing the same is also provided.