A cooker is equipped with a heating chamber having an open part in the front surface and holding an object to be cooked, an opening/closing door having a see-through window and opens and closes the open part, a suction intake opening opened in one of the side walls that faces the heating chamber, an air discharge outlet opened in the other side wall of the heating chamber, and a circulation duct having first and second side surface parts provided outside of the two side walls of the heating chamber and connecting the suction intake opening provided at the first side surface part and the air discharge outlet provided at the second side surface part. The cooker further includes a circulation fan provided inside the circulation duct and drawing in gas inside the heating chamber through the suction intake opening and blows it out through the air discharge outlet.