A cooking apparatus including a cooking chamber having an opening, a door configured to open and close the opening of the cooking chamber, the door including a channel and an inlet to allow communication between the cooking chamber and the channel, and an opening/closing unit to open and close the inlet in the door. A door including a first surface, a second surface spaced from the first surface to define a channel between the first surface and the second surface, an inlet formed in the second surface, the inlet being in flow communication with the channel, an outlet formed in one of the first surface and the second surface, the outlet being in flow communication with the channel, and an opening/closing unit to open and close the inlet in the second surface is also provided.