Disclosed herein is an oven that is capable of discharging hot air generated when cooling a door and heat generated in a cooking chamber through the lower end of the door. The oven includes a door having at least two separated air channels. The air channels comprise at least one first air channel to discharge hot air generated when cooling the door through the lower end of the door, and at least one second air channel to introduce air through the lower end of the door such that the door is cooled. In the housing is mounted a circulating fan. Between the circulating fan and the air channels is connected a channel connecting unit. As the circulating fan is rotated, air flows along the second air channel to cool the door. Hot air generated when cooling the door is introduced into the first air channel through the channel connecting unit, and is then discharged out of the oven through the lower end of the door.