Abstract: An energy-efficient cooker is formed of a main body, an insulation body made integrally with the main body, a base body fitted over the bottom of the main body for making contact with a heat source, and a lid covering an open top of the main body. The main body is provided with a vacuum space which is partially filled with an action fluid to bring about a fast and uniform heat transfer. The insulation body, the base body and the lid are provided with a vacuum space to minimize the loss of heat of the food that is cooked and contained in the main body.