A cooking apparatus includes a cavity unit having therein a cooking chamber and a rear wall plate with an introduction hole section and a discharge hole section; a door on or over the cavity unit, configured to open and close an opening of the cavity unit; and a convection heater unit on or behind the rear wall plate, heating air from the cavity unit through the discharge hole section, and supplying hot air to the cooking chamber through the introduction hole section, wherein the introduction hole section is in a lower part of the rear wall plate, and the discharge hole section is in an upper part of the rear wall plate, separate from the introduction hole section.