To prepare a cooked shell egg containing fluid or soft-boiled albumen on an industrial scale at a low cost while considerably reducing egg breakage ratio.

A shell egg is stored in an egg storage house and heat-treated to obtain a cooked shell egg containing heat-treated albumen (excluding hard-boiled egg). In the above process, the storage of the shell egg in the egg storage house is carried out while removing carbon dioxide in the atmosphere of the egg storage house with a carbon dioxide removing means. The carbon dioxide concentration in the atmosphere of the egg storage house is maintained to 300 ppm by the carbon dioxide removing means. The storage of the shell egg in the egg storage house is preferably carried out until the pH of raw albumen of the shell egg becomes 9.15. The storage period of the shell egg in the egg storage house is set to a level not to lower the Haugh unit of the shell egg of 70.