An oven comprising: an outer case; an inner case disposed in the outer case and having at least one cooking chamber; a cooling fan; and a door installed at the front side of the outer case to open and close the cooking chamber, the door comprising: an inner plate; an outer plate; a frame to enclose the upper sides and the lateral sides of the inner plate and the outer plate, and a plurality of holes formed at an upper side of the frame to allow air discharged by the cooling fan to flow between the inner plate and the outer plate; wherein a blower chamber which is separated from the cooking chamber is provided at the upper side of the inner case in which the cooling fan is disposed, characterised in that a vent hole communicating with the blower chamber is provided at the upper end of the cooking chamber such that hot air of the cooking chamber flows toward the blower chamber through the vent hole; wherein the oven further comprises a blowing guide, wherein the blower chamber is integrally formed with the blowing guide upwardly extending from a bottom surface of the blower chamber such that air discharged by the cooling fan is guided toward the holes formed in the door; wherein the vent hole is disposed in the blower chamber without facing the holes of the door, and a partition member is installed around the vent hole to prevent the hot air discharged from the cooking chamber from being mixed with air discharged by the cooling fan; and wherein the partition member comprises: a first partition plate disposed at an angle such that a rear end thereof is adjacent to a first side of the blowing guide and a front end thereof faces a second side of the blowing guide; and a second partition plate disposed such that a rear end thereof is connected with the first partition plate and a front end thereof faces the door; wherein the vent hole is surrounded by the first and second partition plates (71,72). an outer case; an inner case disposed in the outer case and having at least one cooking chamber; a cooling fan; and a door installed at the front side of the outer case to open and close the cooking chamber, the door comprising: an inner plate; an outer plate; a frame to enclose the upper sides and the lateral sides of the inner plate and the outer plate, and a plurality of holes formed at an upper side of the frame to allow air discharged by the cooling fan to flow between the inner plate and the outer plate; wherein a blower chamber which is separated from the cooking chamber is provided at the upper side of the inner case in which the cooling fan is disposed, characterised in that a vent hole communicating with the blower chamber is provided at the upper end of the cooking chamber such that hot air of the cooking chamber flows toward the blower chamber through the vent hole; wherein the oven further comprises a blowing guide, wherein the blower chamber is integrally formed with the blowing guide upwardly extending from a bottom surface of the blower chamber such that air discharged by the cooling fan is guided toward the holes formed in the door; wherein the vent hole is disposed in the blower chamber without facing the holes of the door, and a partition member is installed around the vent hole to prevent the hot air discharged from the cooking chamber from being mixed with air discharged by the cooling fan; and wherein the partition member comprises: a first partition plate disposed at an angle such that a rear end thereof is adjacent to a first side of the blowing guide and a front end thereof faces a second side of the blowing guide; and a second partition plate disposed such that a rear end thereof is connected with the first partition plate and a front end thereof faces the door; wherein the vent hole is surrounded by the first and second partition plates (71,72). an inner plate; an outer plate; a frame to enclose the upper sides and the lateral sides of the inner plate and the outer plate, and a plurality of holes formed at an upper side of the frame to allow air discharged by the cooling fan to flow between the inner plate and the outer plate; wherein a blower chamber which is separated from the cooking chamber is provided at the upper side of the inner case in which the cooling fan is disposed, characterised in that a vent hole communicating with the blower chamber is provided at the upper end of the cooking chamber such that hot air of the cooking chamber flows toward the blower chamber through the vent hole;