A cooker has an external circulation path outside a heating chamber in which foods are to be placed. A blower sucks in gas inside the heating chamber, and forms, in the external circulation path, a gas flow that makes the sucked gas return to the heating chamber. Downstream of the blower, the external circulation path is provided with an exhaust port, in which a damper is provided. The damper closes the exhaust port during cooking, and opens the exhaust port when a door of the heating chamber is opened. After the damper is changed to a position of opening the exhaust port, the blower continues to operate until a predetermined condition is satisfied.