A cooking device includes a cabinet, a cavity installed in the cabinet and having a cooking chamber therein, a door installed at the cabinet to open and close the cooking chamber, a ventilation passage formed to allow external air of the cabinet to pass through between the cavity and the cabinet so as to be discharged, a blower installed in the ventilation passage, and a cooking chamber air discharge unit for discharging air from the interior of the cooking chamber through the ventilation passage. Because the heated air inside the cooking chamber can be cooled by air which passes through the ventilation passage and then discharged, when the door is opened, heated air cannot be directly discharged to a user from the cooking chamber.