An oven , comprising: a casing to form an external appearance of the oven; a cooking compartment positioned at an inside of the casing, and including a first cooking compartment positioned at an upper side and a second cooking compartment positioned at a lower side; a door to open/close the cooking compartment; a divider positioned in between the first cooking compartment and the second cooking compartment; a first circulating fan and a second circulating fan coupled to rear surfaces of the first cooking compartment and the second cooking compartment, respectively; and an inlet unit (41, 42, 44; 410, 420) to introduce outside air to at least one of the first cooking compartment and the second cooking compartment, the oven further comprising: an outlet pipe (51, 52; 150; 440) to communicate the cooking compartment with an outside so as to discharge a predetermined amount of air inside the cooking compartment corresponding to an amount of air introduced from the outside; and a cooling fan configured to discharge the air inside the cooking compartment to the outside through the outlet pipe (51, 52; 150; 440), characterized in that the outlet pipe (51, 52; 150; 440) is coupled to a front outlet hole adjacently provided at an upper portion of the door , wherein at least one of a door flow path is formed at an inside of the door , and wherein the cooling fan is installed at an outer side of the plurality of cooking compartments as to lead to a cooling of the door by taking in outside air through the at least one door flow path . a casing to form an external appearance of the oven; a cooking compartment positioned at an inside of the casing, and including a first cooking compartment positioned at an upper side and a second cooking compartment positioned at a lower side; a door to open/close the cooking compartment; a divider positioned in between the first cooking compartment and the second cooking compartment; a first circulating fan and a second circulating fan coupled to rear surfaces of the first cooking compartment and the second cooking compartment, respectively; and an inlet unit (41, 42, 44; 410, 420) to introduce outside air to at least one of the first cooking compartment and the second cooking compartment, the oven further comprising: an outlet pipe (51, 52; 150; 440) to communicate the cooking compartment with an outside so as to discharge a predetermined amount of air inside the cooking compartment corresponding to an amount of air introduced from the outside; and a cooling fan configured to discharge the air inside the cooking compartment to the outside through the outlet pipe (51, 52; 150; 440), characterized in that the outlet pipe (51, 52; 150; 440) is coupled to a front outlet hole adjacently provided at an upper portion of the door , wherein at least one of a door flow path is formed at an inside of the door , and wherein the cooling fan is installed at an outer side of the plurality of cooking compartments as to lead to a cooling of the door by taking in outside air through the at least one door flow path . an outlet pipe (51, 52; 150; 440) to communicate the cooking compartment with an outside so as to discharge a predetermined amount of air inside the cooking compartment corresponding to an amount of air introduced from the outside; and a cooling fan configured to discharge the air inside the cooking compartment to the outside through the outlet pipe (51, 52; 150; 440), characterized in that the outlet pipe (51, 52; 150; 440) is coupled to a front outlet hole adjacently provided at an upper portion of the door , wherein at least one of a door flow path is formed at an inside of the door , and wherein the cooling fan is installed at an outer side of the plurality of cooking compartments as to lead to a cooling of the door by taking in outside air through the at least one door flow path . <EOS>