An oven that effectively cools a door by adjusting a position of a cooling guide includes a casing having at least one inhalation hole and at least one ejection hole; a cooking chamber which has an opening and is placed inside the casing; a door that is rotatably coupled to one portion of the casing so as to open/close the opening; a cooling fan that discharges air introduced into the inhalation hole to the ejection hole placed at a front portion of the casing; and an air guide that is installed adjacent to the ejection hole so as to change a direction of air driven by the cooling fan. The cooling guide is installed not to disturb the flow of air that passes through the door so that the door using minimum sheets of glass can be provided.